NCERT Solutions Class 5 The World Around Us Chapter 7 Energy How Things Work

F R E E S T U D Y M AT E R I A L F O R E V E R Y S T U D E N T

CLASS 5 · THE WORLD AROUND US

NCERT Solutions

Chapter 7: Energy—How Things
Work

NCERT Textbook — Our Wondrous World

BOOK PAGES SECTIONS QUESTIONS MEDIUM

114 – 130 28 45 English

Solutions, notes, sample papers & more at 54 pages

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

CLASS 5 · THE WORLD AROUND US · OUR WONDROUS WORLD

NCERT Solutions — Chapter 7: Energy—How Things
Work
Chapter 7 of Our Wondrous World opens Unit 4, Things Around Us. It begins in a kitchen — food cooking in a
pan, vegetables being chopped — and asks one simple question: what makes all this happen? The answer is
energy. The chapter takes you through what energy does, food as our own fuel, fuels like petrol, gas,
wood and coal, electricity and how to use it safely, and clean energy from the Sun, wind and flowing
water. It carries 9 Activities and one Extension Activity, two Discuss boxes, six Think prompts, three Write
prompts, and the closing Let us reflect set of 7 items. There is no separate exercise at the end — the
questions are spread right through the chapter.

TEXTBOOK BOOK PAGES

Our Wondrous World (Class 5) 114 – 130

SECTIONS QUESTIONS

28 45

MEDIUM

English

In-text Question — Page 114

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

What is Energy? — observing a kitchen

Q1 In a kitchen, we can see a variety of activities. Let us observe a kitchen for some
time. Write your observations and the questions that come to your mind in the
table given below.

The kitchen picture on page 114 — redrawn.

I OBSERVE I WONDER

The food is getting cooked. How is it being cooked?

Look carefully at the kitchen picture on page 114. A woman is stirring food in a kadhai on the
stove. A man is chopping cucumber and tomatoes on a board. There is a covered vessel on the
counter and sunlight coming in through the window.
Here is the table filled in. The first row is the book's example.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

I OBSERVE I WONDER

The food is getting cooked. How is it being cooked?

The stove has a flame under the pan. Where does the flame come from? What is
burning?

Steam is rising from the hot food. Why does food give off steam when it gets hot?

The man's hand moves the knife and the vegetables get cut. How is his hand able to move like that?

Sunlight is coming in through the window and lighting up the Can sunlight do any other work besides giving
kitchen. light?

Your own table may have other rows — a mixer running, a fridge humming, a light burning. Any true
observation is correct.

What all these rows have in common: in every single row, something is happening.
Food gets hot. Steam rises. A hand moves. A room lights up. Nothing happens by
itself. Something must make it happen — and that something is called energy. That
is exactly the question this chapter answers.

Try this at home: Stand quietly in your kitchen for two minutes with a pencil. Write
down five things you see happening. Then, next to each one, write the question it
makes you ask. That is what a scientist does — notice first, wonder second.

In-text Question — Page 115
Activities we see in nature and society

Q1 From your observation write down at least three things that you have noticed: •
Moving • Providing light • Making a sound • Making things cool • Making things hot

Under each heading, write things you have actually seen. Here is a filled sample.

Page 3 of 54

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

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WHAT IS THINGS I HAVE NOTICED
HAPPENING
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Moving
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Providing light The Sun · a tube light · a diya · a torch · a mobile phone screen

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Making a sound The school bell · a dholak · a scooter horn · a radio · thunder

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Making things hot A gas stove · an iron · a geyser · the Sun on a summer afternoon · a wood fire

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Whyemthese five headings matter: These are the five jobs energy does. Whenever
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Did you know? The Flying Snake, which lives in Indian forests, can glide through the
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air by flattening its body. Even that gliding is movement — so it too needs energy,
and the snake gets it from its food.

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Now match a few everyday things to the energy behind them.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

WHAT WE SEE WHAT IS HAPPENING WHERE THE ENERGY COMES FROM

A boy running Moving The food he ate

A scooter on the road Moving Petrol

The Sun at noon Giving light and heat The Sun itself

A bulb glowing Giving light Electricity

A dholak being played Making sound The hand that strikes it — that is, food

Water boiling on a stove Getting hot Cooking gas burning

A fridge keeping milk cold Getting cool Electricity

The idea in one sentence: Nothing happens on its own. If something changes — if
it starts moving, glows, sounds, warms or cools — energy has been used to make
that change.

For your discussion: Ask each other, “If nothing had any energy at all, what would
the world be like?” Nothing would move. No sound. No light except… nothing at all,
because even the Sun's light is energy. That is why the chapter says energy is what
makes our world active and alive.

Activity 1 — Page 116
The balloon, and the Balloon Air Rocket

ACTIVITY

Q1 1. Take a balloon and blow into it until it fills up. 2. Hold it tightly. 3. Then, release
the mouth of the balloon and observe what happens.

What you will see: the moment you let go, the balloon shoots away across the room. It flies
about in a wobbly, twisting path, making a hissing sound, and it drops down only when all the
air has come out.
How to do it:

1. Blow air into the balloon until it is nicely full. Do not fill it so much that it may burst.
2. Pinch the neck tightly between your thumb and finger. Hold it up, away from your face.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

3. Now open your fingers — but do not throw the balloon. Just let it go.
4. Watch which way it flies, and listen to the sound.

WHAT I WATCHED WHAT I OBSERVED

The air It rushes out of the neck in a fast stream. You can feel it if you hold your palm near.

The balloon It flies off in the opposite direction to the escaping air.

Its path Not straight — it twists and turns, because the neck keeps flapping about.

The sound A hiss or a squeal, made by the air pushing through the narrow neck.

The end When the air is finished, the balloon is limp and it falls to the floor.

Why it happens: When you blow into the balloon you squeeze a lot of air into a
small space. The stretched rubber presses on that air. The moment you open the
neck, the air rushes out. As the air rushes backwards, it pushes the balloon forwards.
In the book's words — when air rushes out of the balloon, it pushes the balloon
forward. This is how the movement of air generates energy.

Feel it yourself: Blow up the balloon again and hold it near your cheek before you
let go. When you release it, you feel the air on your skin. That moving air is doing the
pushing.

Q2 Extension Activity: Balloon Air Rocket — 1. Fill the balloon with air and attach it to a
straw with tape. 2. Pass a string through the straw. 3. Hold the ends of string with
someone's help. 4. Now, release the balloon and watch it move along the string.

What you will see: the balloon zooms along the string from one end to the other, carrying the
straw with it. This time it does not wobble about, because the string keeps it going straight.
How to make it:

1. Cut a drinking straw to about half its length.
2. Thread a long string (3 to 5 metres) through the straw.
3. Tie or hold the two ends of the string tight, across the room. Ask a friend to hold one end.
4. Blow up the balloon. Pinch the neck so the air cannot escape.
5. With your other hand, stick the balloon to the straw with two strips of tape, with the neck
pointing backwards.
6. Slide the straw to one end of the string. Check that the string is pulled tight.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

7. Let go of the neck.

Rocket flies this way
String held tight Straw

Air rushes out this way

Tape holds the balloon to the straw

The air goes one way, the balloon goes the other way — and the string keeps the path straight.

Why it happens: It is exactly the same push as in Activity 1. The air rushes
backwards out of the neck; the balloon is pushed forwards. In the first activity the
balloon could go anywhere. Here the straw is threaded on the string, so the balloon
can only go along the string. That is why it travels neatly from one end to the other. A
real rocket works in the very same way — it pushes hot gas out of the back and is
pushed forward.

If it does not run well: pull the string tighter, use a lighter balloon, make sure the
tape is not stuck to the string, and keep the neck of the balloon pointing straight
backwards along the string.

Think — Page 116
Making the balloon rocket faster or slower

THINK

Q1 What would you change in the activity to make the toy move faster or slower?

To make it faster, put more air in the balloon and take weight away. To make it slower, put
less air in and add weight or rubbing.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

WHAT I TO GO FASTER TO GO SLOWER
CHANGE

Air in the balloon Fill it fully — more air means a Fill it only half
bigger push

Size of the Use a bigger balloon Use a small balloon
balloon

The string Pull it tight and straight, and keep it Let it sag, or use a rough, thick rope
smooth

The straw A short, smooth, light straw slides A long or bent straw rubs against the string
easily

Weight carried Carry nothing extra — use one small Tape a coin or a small clip to the balloon
piece of tape

The slope Tie the far end a little lower, so it Tie the far end higher, so it must climb
runs downhill

Mouth of the Let the whole neck open at once Fit a narrow straw piece in the neck so air
balloon trickles out slowly

Why these work: Two things decide the speed. One — how hard the escaping air
pushes. More air, packed tighter, pushes harder. Two — how much is holding the
rocket back. Extra weight and rubbing hold it back. So: bigger push and less holding
back means faster; smaller push and more holding back means slower.

Try it as a race: Make two rockets on two strings side by side. Fill one balloon fully
and the other only half. Release both together. The full one always wins. Change only
one thing at a time — that is how a proper test is done.

Activity 2 — Page 117

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Rubber Band Guitar
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ACTIVITY

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the bands at one end to raise them. 4. Pluck the bands and listen to the sounds

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What you will hear: each band gives a clear twanging note. You can see the band blur as it

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4. Push a pencil or a ruler under all the bands

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5. Pluck one band — pull it up a little and
6. Listen. Then pluck the others by one.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Why it happens: When you pluck a band, it starts to shake to and fro very fast. That
fast shaking is called vibration. The vibrating band shakes the air around it, and that
shaking air reaches your ear — and you hear a sound. The book says it plainly:
plucking the rubber bands makes them vibrate and produce sounds, and this is
known as sound energy. The hole and the hollow box make the sound louder,
because the air inside the box shakes along with the band. That is why a real guitar,
a sitar and a dholak are all hollow.

Check it yourself: Pluck a band and touch it gently with your finger. Two things
happen at once — you feel the shaking, and the sound stops. No vibration, no
sound.

Think — Page 117
Thin bands and thick bands

THINK

Q1 What happens if you use thinner or thicker rubber bands? Do they sound different?

Yes, they sound different. A thin band gives a high, sharp, thin sound. A thick band gives a
low, deep, heavy sound.

BAND HOW IT SHAKES THE SOUND YOU HEAR

Thin band Shakes very fast High and sharp — like a small bell

Thick band Shakes more slowly Low and deep — like a big drum

Band pulled tight Shakes faster The note goes higher

Band left loose Shakes slower The note goes lower

Why it happens: A thin band is light, so it shakes to and fro quickly. Fast shaking
makes a high note. A thick band is heavier, so it shakes to and fro more slowly. Slow
shaking makes a low note. Tightening a band has the same effect as making it
thinner — it shakes faster and the note rises.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Look at a real instrument: On a sitar, a guitar or a tanpura the strings are not all
the same. Some are thin and some are thick, and each gives a different note. Your
box guitar works on exactly the same idea.

Activity 3 — Page 117
Sun-powered Water Warmer

ACTIVITY

Q1 Sun-powered Water Warmer — 1. Fill two cups with water. 2. Place one cup in the
sunlight and another in the shade. 3. Wait for 15 – 20 minutes and then touch the
water in both the cups. What do you notice?

What you will notice: the water in the cup kept in the sunlight feels clearly warm. The water in
the cup kept in the shade still feels cool. Both cups had the same water at the start, so the Sun
must have done the warming.
How to do it properly:

1. Take two cups of the same size and the same colour.
2. Fill both with the same amount of water from the same pot, at the same time.
3. Put one cup in bright sunlight — a sunny windowsill or the school ground.
4. Put the other in the shade, close by, so the air around both is the same.
5. Wait 15 to 20 minutes. Do not move them.
6. Now dip a finger in each cup, one after the other, and compare.

CUP WHERE IT WAS KEPT HOW THE WATER FEELS AFTER 20 MINUTES

Cup 1 In the sunlight Warm — clearly warmer than when you poured it

Cup 2 In the shade Still cool — almost the same as at the start

Why it happens: Sunlight is not just light. It carries heat energy as well. When
sunlight falls on the cup and the water, that heat passes into the water and the water
gets warm. The cup in the shade gets no sunlight, so nothing warms it. As the book
says — this shows how the sunlight gives us heat energy.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Where you have already seen this: water in a black tank on a roof turns hot by
afternoon; a solar water heater on a roof gives hot water without any gas or
electricity; and a solar cooker cooks dal using only the Sun. Do you know? The
Bhadla Solar Park in Rajasthan is one of the largest solar power plants in the world.

In-text Questions — Page 118
Sources of Energy — the teacher's questions

Q1 “Let us do an activity — stand up and stretch your arms. Now, jump! Run in place.”
“How are you able to move?”, she questioned.

We are able to move because of energy — and we get that energy from the food we eat.
Follow what happens, step by step.

1. In the morning you eat breakfast — roti, rice, dal, milk, a banana.
2. Your body breaks that food down inside you.
3. The food gives your body energy.
4. Your muscles use that energy to pull on your bones.
5. So your arms stretch, your legs push, and you jump and run.

Food → energy in the body → muscles work → we move

Why food is the answer: The class had all eaten breakfast. That is why they could
stand, stretch, jump and run. Without food there would be no energy, and without
energy there would be no movement. That is exactly what the teacher wanted the
class to notice.

Did you know? Our brain uses energy even when we are simply sitting, sleeping or
thinking. So the body is never really switched off — it keeps spending energy all day
and all night.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Q2 “How do you feel when you are hungry? When we do not eat, we may feel tired, and
when we eat, we feel active and ready to play. What do you think could be the
reason?”

The reason is energy. Food gives us the energy we need. When we have not eaten, the body is
short of energy and we feel tired. After we eat, the body has energy again and we feel active.

SITUATION HOW WE FEEL THE REASON

We have not eaten for a long Tired, weak, sleepy, unable to run The body is running low on energy
time about

We have just eaten a proper Active, cheerful, ready to play The food has given the body fresh
meal energy

Think of it like this: A scooter cannot run when its tank is empty; fill petrol and it
runs again. Our body is the same. Food is our petrol. That is why the chapter calls
food a source of energy.

A useful habit: Never skip breakfast on a school day. The first meal of the day is the
one that has to carry you through your classes and your games period.

In-text Question — Page 119
Animals and their energy

Q1 Now, let us think about animals. A dog running, a bird flying … just like us, animals
also need energy to move, fly, swim, run, find food and protect themselves. But
from where do they get this energy?

Animals also get their energy from food. Food is a source of energy for all living things.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

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ANIMAL WHAT IT DOES WHERE ITS ENERGY COMES FROM

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Roti, milk, meat and scraps it eats

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Sparrow Flies, builds a nest
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Grain, seeds and small insects

Cow Walks, chews, gives milk Grass and fodder

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Fish Swims Water plants and tiny water creatures

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Carries loads much bigger Bits of food it gathers

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Why every animal needs it: Moving, flying, swimming, hunting and hiding are all

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And where does the food get its energy? Plants make their food using sunlight.

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Animals eat plants, or eat animals that ate plants. So in the end almost all our
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Think — Page 119
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They need fuel — petrol or diesel. Fuel is to a vehicle what food is to us.
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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

VEHICLE WHAT IT USUALLY RUNS ON

Scooter, motorcycle, car Petrol

Bus, truck, tractor Diesel

Auto-rickshaw CNG or petrol

Electric car, e-rickshaw, electric bus Electricity, stored in a battery

Bicycle The rider's own energy — that is, food

Why fuel is needed: A vehicle is a machine, and a machine cannot move by itself.
Burning a little petrol or diesel inside the engine releases energy, and the engine
turns that energy into the turning of the wheels. When the tank is empty there is no
energy left, and the vehicle stops.

Notice the bicycle: it is the only one in the list with no tank. The energy comes from
the rider's legs, and the rider's legs got it from food. That is why a bicycle makes no
smoke at all.

Write — Page 119
Cooking at home

WRITE

Q1 How is food cooked in your house?

Write about your own kitchen. Say what you cook on, what fuel it uses, and where that fuel
comes from.
Sample answer: “In my house food is cooked on a gas stove. The stove is joined by a rubber
pipe to an LPG cylinder that we buy from the gas agency. When my mother turns the knob, the
gas comes out and she lights it with a lighter. The blue flame heats the pan and the food cooks.
On some days, when we make a lot of food for a function, my grandmother cooks on a chulha in
the courtyard using firewood.”

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

WAY OF COOKING FUEL USED GOOD AND NOT SO GOOD

Gas stove LPG cooking gas from Quick and clean; but it is a fuel that must be bought and
a cylinder it will not last for ever

Chulha Firewood, dry cow- Cheap and easily found in a village; but it gives smoke
dung cakes that stings the eyes and harms the lungs

Angeethi / sigri Coal Stays hot a long time; but it makes a lot of smoke and
harmful gases

Induction plate, Electricity No smoke in the kitchen; but most electricity is still made
electric kettle by burning coal somewhere else

Solar cooker Sunlight — free No fuel, no smoke, no cost; but it works only on a sunny
day and cooks slowly

What to notice: Every one of these is a way of getting heat. The pan does not care
where the heat came from. What changes is the fuel — and each fuel has its own
cost, and its own effect on the air we breathe.

Discuss — Page 120
Fuel at home

DISCUSS

Q1 What kind of fuel do you use at home for cooking?

Different homes in India use different cooking fuels. Say which one your home uses, and why.
Sample answer: “We use LPG cooking gas. It comes in a red cylinder. We chose it because it
lights at once, gives no smoke in the kitchen, and the flame can be made big or small.”
These are the fuels your classmates are likely to name:

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

FUEL WHERE IT IS USED WHY PEOPLE USE IT

LPG cooking gas (cylinder or Most towns and, more and more, Fast, clean, easy to control
pipeline) villages

Firewood Villages, hill areas, outdoor Available nearby and costs nothing
cooking to collect

Cow-dung cakes (uple) Farming households Made at home from what the cattle
give

Coal in an angeethi Some homes and roadside shops Stays hot for a long time

Kerosene stove Some homes Small, easy to carry

Electricity (induction plate) Town flats No flame, no smoke in the kitchen

Sunlight (solar cooker) Sunny places, some schools and Free, and it does not pollute at all
hostels

Why the answers differ: A family uses the fuel that it can most easily get and
afford. Wood is easy in a forest village. Gas is easy in a town. So there is no single
right answer here — but there is a cleaner answer and a smokier one, and that is
what the next question is about.

Q2 What are the problems using too much wood or coal?

Burning a lot of wood or coal makes smoke and harmful gases. That dirties the air, harms
our health, and forests are cut down to get the wood.

Smoke inside the kitchen. A wood or coal fire fills the room with smoke. It makes the eyes
burn and water. Breathing it every day gives coughs and chest illness — and the person
cooking breathes the most of it.
Dirty air outside. The smoke carries harmful gases and fine soot into the air of the whole
village or town. This is pollution — air that has been made dirty.
Trees are cut. Firewood comes from trees. If everyone burns a lot of wood, forests shrink.
Fewer trees means less shade, more soil washed away, and homes lost for birds and
animals.
Coal will not last. Coal is dug out of the ground. It took millions of years to form. Once we
burn it, it is gone; nobody can make more.
Hard, slow work. Wood and coal have to be collected, carried, stacked and kept dry. The fire
is slow to light and hard to control.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Ash and dirt. The pots turn black underneath and there is ash to clean up every day.

Why the book warns us: Wood and coal do give good heat — that is not in doubt.
The trouble is what comes out along with the heat. As the chapter says, burning
wood or coal creates smoke and pollution, so we must use it carefully.

What helps: a smokeless chulha with a chimney that leads the smoke outside; a
solar cooker on sunny days; cooking gas where a family can get it; keeping a window
open while cooking; and planting a tree for every one that is cut.

Activity 4 — Page 120
Understanding How Fuel Works — the two diyas

ACTIVITY

Q1 Understanding How Fuel Works — 1. Place two diyas (lamps) on a flat surface. 2. In
Diya 1 — place a cotton wick without any oil, and in Diya 2 — place a cotton wick
and pour some oil around it. 3. Light the wicks in both the diyas under adult
supervision. 4. Observe what happens to the diyas.

What you will see: both wicks catch fire at first. Diya 1, with no oil, burns for only a few seconds
— the dry cotton itself burns up, turns black and the flame dies. Diya 2, with oil, keeps burning
with a steady yellow flame for a long time, and its wick does not get used up.
How to do it (with an adult beside you):

1. Put two clay diyas side by side on a plate or a stone floor, away from paper and cloth.
2. Roll two wicks of the same size from clean cotton. Put one in each diya.
3. Leave Diya 1 dry. Pour a spoon of oil into Diya 2 so the wick soaks in it. Wait a minute for the
oil to climb up the wick.
4. An adult lights both wicks at the same moment.
5. Watch both flames. Count slowly, or look at a clock.

Page 18 of 54

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

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a
Diya 1 — no oil
.
Diya 2 — with oil com
m long
burns steadily,sefor
m
flame dies in seconds
a
e m . co agl
g l as
a
Same wick, same flame at the start — only one of them has a fuel supply.

m a s
.co agl
WHAT I WATCHED DIYA 1 (NO OIL) DIYA 2 (WITH OIL)

se m
Does it light?
g l a
a
Yes Yes

Size of the flame Small and weak Tall and steady

co m
m .
se
How long it burns A few seconds only Many minutes, until the oil runs out

comafterwards
The .wick l a
Still there,gjust charred at the tip
m a
ase
Burnt black and crumbly

agl
m
Safety first: Do this only with an adult. Tie back long hair, roll up loose sleeves, keep

a se
com l
a mug of water nearby, and put the diyas on a stone or metal plate — never on
. a g
m
ase
paper or cloth.

agl

co m
.
Q2 (a) Which diya burns longer? Why?

e m
com g l as
. a
sem

a
agl
Diya 2 — the one with oil — burns much longer. It burns longer because it has a fuel to keep
the flame going. Diya 1 has no fuel, so its flame dies as soon as the dry cotton itself is burnt up.
.c
s e m
om la
What is happening inside Diya 2, step by step:

1. The bottom of the wick sits inm . c a g
s e the oil.

a gla the oil up along its threads, the way a cloth soaks up water.
2. The cotton wick slowly draws
3. At the top, the heat of the flame turns that oil into a vapour.

co m
m .
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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

4. The vapour burns, and that burning is the flame you see.
5. As soon as a little oil is used, more oil climbs up the wick to take its place.
6. So the flame is fed again and again — and it keeps burning until the diya is empty.

Diya 1: dry wick → wick itself burns → flame goes out in seconds

Diya 2: oil climbs the wick → oil burns → more oil comes up → flame keeps burning

The idea to carry away: A flame does not live on its own. It must be fed. Whatever
we feed it — oil, gas, wood, coal, petrol — is called a fuel. No fuel, no flame.

Q3 (b) What is acting as a fuel here?

The oil is the fuel. That is exactly what the book says on the next page: “The oil is the fuel.”
Do not get confused by the wick. The wick is only the pipe that carries the oil to the flame. It is
not the fuel itself — which is why the wick is still there after the diya has burned for a long time,
but the oil is gone.

PART ITS JOB

Clay diya Holds the oil safely

Cotton wick Carries the oil up to the flame, drop by drop

Oil The FUEL — it burns and gives the light and heat

Air Fuel needs air to burn; cover the flame and it goes out

Where else you meet fuel: The chapter lists them — we use different fuels in daily
life for cooking, for lighting diyas and for running vehicles. Cooking gas in the stove,
wood in the chulha, petrol in the scooter, diesel in the tractor and oil in the diya are
all fuels. Each one is a store of energy waiting to be released by burning.

Try it: Light Diya 2 and then place a glass tumbler upside down over it. The flame
grows dim and goes out, even though there is plenty of oil left. Fuel alone is not
enough — burning also needs air.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

In-text Question — Page 121
Electricity

Q1 What are the things in your home that need electricity to work?

Many things at home run only on electricity — the fan, the tube light and bulbs, the
television, the fridge, the mixer, the iron, the water pump, the mobile charger, the cooler, the
washing machine and the doorbell.
Sort them by the job the electricity does:

WHAT THE ELECTRICITY DOES THINGS AT HOME

Makes things move Fan, mixer, washing machine, water pump, cooler

Gives light Tube light, LED bulb, torch, mobile screen

Makes sound Radio, television, doorbell, mobile phone

Makes things hot Iron, geyser, electric kettle, induction plate, room heater

Makes things cool Fridge, air conditioner, cooler

Notice something: Electricity can do all five jobs of energy. That is why it has
become so useful. One set of wires reaching your house can move a fan, light a bulb,
sound a bell, heat an iron and cool a fridge.

An easy way to find them all: Look for a plug and a wire. If a thing has a plug going
into a socket, or a switch on the wall, it needs electricity.

Activity 5 — Page 121

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Five things that run on electricity

ACTIVITY

Q1 Walk around your home or classroom. Identify five things that run on electricity. Fill
in the following table.

S. DEVICE WHAT WHAT IT REQUIRES?
NO. IT (LIGHT/SOUND/HEAT/MOVEMENT/COOLING/OTHER)
DOES?

1. Fan Blows Movement
air

2.

3.

4.

5.

6.

Walk round with a pencil and look for anything with a plug, a wire or a wall switch. Here is the
table filled in. Row 1 is the book's example.

S. NO. DEVICE WHAT IT DOES? WHAT IT REQUIRES?

1. Fan Blows air Movement

2. Tube light Lights up the room Light

3. Radio / television Plays songs and shows programmes Sound (and light, for the picture)

4. Electric iron Presses the creases out of clothes Heat

5. Refrigerator Keeps milk and vegetables from spoiling Cooling

6. Mixer-grinder Grinds chutney and masala Movement

Your list will depend on your own home or classroom. A water pump, a mobile charger, a doorbell, a
cooler, a computer or a projector are all correct answers.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

What the last column really means: it is asking what the device gives us out of the
electricity — a push and a turn (movement), brightness (light), a noise (sound),
warmth (heat) or coldness (cooling). The electricity is the same in every wire. What
changes is the machine that uses it.

Did you know? Using less energy to do the same work is called energy efficiency.
An LED bulb gives the same light as an old bulb but uses much less electricity. So
changing one bulb saves electricity every single day.

Q2 From the above examples, did you notice that electricity can be used for movement,
and producing sound, light and heat?

Yes. From this one table it is clear that electricity can do every job that energy does — it
can move things, make sound, give light, make heat, and even make things cool.

Movement — fan, mixer

Light — tube light, LED

Electricity Sound — radio, bell

Heat — iron, geyser

Cooling — fridge, AC

One kind of energy in the wire, five different jobs coming out of it.

Why this is important: Because electricity can do all five jobs, one supply of
electricity can run a whole house, a whole school, and whole factories. The chapter
reminds us that industries use electricity to run machines that make the clothes,
toys, books, food and even the scooters and cars we use.

Page 23 of 54

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

co m
m.
But use it with care: electricity is very useful and also dangerous. Never touch wires

m l a se
or the parts of a plugged-in device. Never put fingers, pens or sticks into a socket.
o g
Stay away.cfrom broken wires, fallen poles, electric boxes and transformers,
a
m
and tell
an a
l se at once. Never try to repair anything yourself.
ag
adult

co m
em . ag
as
Think — Page 122
A day without electricity
a g l

m
THINK

co
em.
m l as
.co g
What would your day be like if there was no electricity at all?
a
Q1

a s em
a l
gANSWER
s
The day would be far harder and much slower. No fan, no light after dark, no fridge, no
m a
.co agl
pump, no phone, no TV — and many people's work would simply stop.

se m
a
Walk through the day, hour by hour.

a g l
1. Morning. No alarm on the phone. The motor cannot pull water to the tank, so we must draw
water by hand.

co m
.
2. Kitchen. The fridge is off, so yesterday's milk and vegetables begin to spoil. No mixer — the
m
m
chutney must be ground on a stone.
as e
.co a g l
em
3. Getting ready. No iron for the uniform. No geyser for hot water.

l a s4. School. The classroom is hot and dark. No fan, no lights, no computer, no projector, and the
ag water cooler does not work.
5. Shops and hospitals. Shop freezers thaw. Hospitals must run on generators, and machines
se m
com g l a
. a
and lights there are needed to save lives.
m
ase
6. Factories. Machines stop, so nothing gets made and people lose a day's work.

a gl
7. Evening. Homework has to be done before sunset, or by a diya or a candle.
8. Night. Streets are dark. Homes are quiet and hot. People sleep on the terrace to catch the
breeze.
co m
m .
m as e
.co a g l
Why we feel it so much: Electricity is not one machine — it is behind almost every

se m machine. When it goes, it takes light, movement, sound, heat and cooling with it all
g l a
a at once. That is exactly why the chapter says our lives have become so easy with
c
m .
e
electricity.
m a s
e m . co agl
g l as
a

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m .
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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

One good thing to notice: people managed for thousands of years without it.
Traditional Indian houses had thick walls and small windows, so they stayed cool in
summer and warm in winter. A courtyard, a chatai on the terrace, a hand fan, an
earthen matka for cold water — old ideas that still work in a power cut.

In-text Question — Page 123
Sources of electricity that do not pollute

Q1 Most of the electricity we use comes from burning fuels like coal. However, burning
coal creates a lot of smoke and harmful gases that pollute the air… Nevertheless,
there are other sources we can use to produce electricity that do not cause
pollution. Can you find out what these sources are?

Yes — the Sun, the wind and flowing or falling water. Electricity made from these three does
not fill the air with smoke, so it is called clean energy.

SOURCE THE MACHINE HOW IT WORKS WHERE YOU SEE IT IN
THAT CATCHES IT INDIA

The Sun Solar panel The flat black panel takes in Bhadla Solar Park,
sunlight and turns it into Rajasthan — one of the
electricity largest in the world

Wind Windmill (wind The wind pushes the long blades Wind farms in Tamil Nadu,
turbine) round, and the turning makes Gujarat, Karnataka
electricity

Flowing or Turbine in a dam or Fast-moving water spins a wheel Dams like Bhakra Nangal;
falling water on a river called a turbine, and that makes hill gharaats that grind
electricity grain

Coal → electricity + smoke and harmful gases

Sun, wind, water → electricity + nothing harmful

Why these three do not pollute: Nothing is burnt. A solar panel just sits in the light.
A windmill just turns. A turbine just gets pushed by water. Where there is no burning,
there is no smoke. And there is one more good thing — sunshine, wind and river
water come back day after day, while coal, once dug up and burnt, is gone for ever.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Did you know? Cochin International Airport in Kerala was the first airport in the
world to be run entirely on solar energy. A whole airport, with all its lights and
machines, running on sunshine.

Think — Page 123
Generating Energy from the Sun, Wind and Water

THINK

Q1 Place a small damp cloth in the Sun. Keep another damp cloth in the shade. Which
one do you think will dry first? Why?

The cloth in the Sun dries first. It dries faster because sunlight gives heat, and heat turns the
water in the cloth into water vapour more quickly.
How to test it:

1. Take two pieces of the same cloth, of the same size.
2. Dip both in water and squeeze both the same amount.
3. Spread one in bright sunlight and one in the shade, at the same time.
4. Touch both after 15 minutes, then after 30 minutes.

TIME CLOTH IN THE SUN CLOTH IN THE SHADE

After 15 minutes Only slightly damp Still clearly wet

After 30 minutes Dry, and warm to touch Still damp in the middle

Why it happens: To dry, the water in the cloth must leave it as an invisible gas called
water vapour. Heat helps the water do that. Sunlight brings heat, so the water in the
sunlit cloth turns into vapour quickly and goes into the air. The cloth in the shade
gets very little heat, so its water leaves slowly. A breeze helps too — it carries the
vapour away and lets more water leave.

Where you have seen this: clothes on the line dry fastest on a hot, windy
afternoon. Papads and mango slices are put out in the Sun to dry. Salt is made by
letting sea water dry in the Sun. All of it is free energy from the Sun, and no plug is
needed.

Page 26 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Activity 6 — Pages 123–124
Pinwheel

ACTIVITY

Q1 Pinwheel — 1. Take a square piece of paper. 2. Draw its two diagonals with the help
of a ruler. 3. Now, you have four equal parts. 4. Cut halfway along each of the four
lines. 5. Fold each corner and pin it to the stick as shown in the image. 6. Now, hold
your pinwheel in the wind. If there is no wind, hold it up and run with it.

1 2 3 4 5

Steps 1 to 5 of making the pinwheel, as pictured on page 123.

How to make it, step by step:

1. Cut a square of stiff paper, about 15 cm on each side. A thin card or an old greeting card
works best.
2. With a ruler, draw a line from one corner to the opposite corner. Do the same for the other
pair of corners. These two lines are the diagonals — the lines that join opposite corners.
They cross at the centre.
3. The square is now divided into four equal triangles.
4. Cut along each diagonal from the corner towards the centre — but stop halfway. Do not cut
right up to the centre, or the paper will fall into four pieces.
5. You now have four loose corner points. Take one point from each cut and fold it in to the
centre. Hold all four down together with your finger.
6. Push a pin through all four folded points and the centre of the paper, and then into the side
of a stick, a pencil eraser or a thin bamboo.
7. Loosen the pin a little so the paper can spin freely.
8. Hold it up in the wind. If there is no wind, hold it up and run.

Page 27 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

1. Square 2. Two diagonals 3. Cut halfway
4. Pin to a stick

Square → diagonals → four half-cuts → fold four corners in and pin them to a stick.

If it will not spin: the pin is too tight — pull it back a little. Or the folded corners are
too heavy — fold in only the tips. Or the paper is too soft and floppy — use a stiffer
card.

Q2 What happens to your pinwheel?

The pinwheel spins round and round. When the wind is strong it whirs fast and its colours blur
together. When the wind drops it slows and stops. If there is no wind, it starts spinning the
moment you run with it.

WHAT I DO WHAT THE PINWHEEL DOES

Hold it still in calm air It does not move at all

Hold it in a gentle breeze It turns slowly

Hold it in a strong wind It spins fast and makes a soft whirring sound

Run with it, holding it up It spins, because I have made the air rush past it

Blow on it from the side It turns; blow from the other side and it turns the other way

Page 28 of 54

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

co m
m.
Why it happens: Each folded corner makes a small slanting flap, like a tiny sail. The

m l a se
moving air cannot pass straight through the flap, so it pushes on the slant. Every flap
o
m
gets pushed.c the same way round, and the whole wheel turns. Soagthe moving air has
l a sework — which means the wind is a source of energy. That is what the book
g
done
aconcludes: the pinwheel rotated, the paper burned and the water wheel spun, and
all these show that the wind, the Sun and water are sources of energy that make
co m
things work.
em . ag
g l as
a
A pinwheel grown big: A windmill is nothing but a giant pinwheel. The wind pushes
its long blades round, and the turning is used to make electricity. Old sailing ships
co m
used the same wind — traders from Gujarat and Tamil Nadu sailed to Africa, Arabia
em.
m l as
.co g
and Southeast Asia using the power of the wind.
m a
l a se
a g
Activity 7 — Page 124
m a s
Sunlight in Focus
m .co agl
l a se
a g
ACTIVITY

Sunlight in Focus — 1. Take a piece of paper and a magnifying glass. 2. Place the
co m
.
Q1

e m
as
paper in direct sunlight and use the magnifying glass to focus the light on it. Tip:
m l
.co g
The activity has to be done under adult supervision.

em a
a s
agl ANSWER
How to do it — only with an adult standing beside you:
se m
com g l a
near paper, cloth or dry leaves. em
1. Choose an open, sunny spot outdoors.
. Stand on stone or bare ground, never on grass or
a
l s
ayou
a
2. Keep a mug of water beside g before you begin.
3. Lay a small piece of paper flat on the ground or on a stone. A dark or newspaper piece works

co m
.
best.

em
as
4. Hold the magnifying glass between the Sun and the paper.
m l
.co a g
5. Move the glass slowly up and down. You will see a circle of light on the paper. It grows bigger

a s em and smaller as you move.
agl 6. Stop when the circle is at its smallest and brightest — the size of a dot. That dot is the focus,
.c
the point where all the light is gathered.
s e m
m a
. co agl
7. Hold the glass steady there and watch the dot.

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a

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Sun

Bright hot dot
on the paper
Magnifying glass
All the light that falls on the wide lens is gathered into
one tiny point.

The lens gathers a wide beam of sunlight into a single small spot.

Safety rules, and they matter: Never look at the Sun through the glass — it can
damage your eyes. Never point the hot dot at anyone's skin, clothes or hair. Do it on
bare ground, with an adult and water at hand, and put the glass away face down
when you finish so it cannot start a fire by itself.

Q2 3. What happens to your paper?

The paper grows very hot at that one bright dot. It turns brown, then black, then starts to
smoke, and if you hold the glass steady it catches fire and burns a small hole.

TIME WHAT HAPPENS AT THE DOT

At once A very bright small spot appears

After a few seconds The paper turns brown at that spot

A little later The brown mark turns black and a thin thread of smoke rises

If held steady The paper catches fire and a small hole burns through

Page 30 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Why it happens: Sunlight carries heat. Spread over a whole page, that heat only
makes the paper pleasantly warm. The magnifying glass bends all the light that
lands on it and gathers it into one tiny dot. Now the heat that was spread over the
whole lens is packed into a spot smaller than a grain of rice. Squeezed into that tiny
place, the heat becomes strong enough to burn the paper. Nothing was added — the
same sunlight was simply concentrated, that is, gathered into one place.

The same idea, put to work: a solar cooker uses shiny sheets to gather sunlight
into the pot, and cooks dal and rice with no fuel at all. Bigger solar plants use rows
of mirrors to gather sunlight and make steam. The Sun gives more energy to Earth
in one hour than all the people on Earth use in a whole year.

Activity 8 — Page 124

Page 31 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Water Wheel

ACTIVITY

Q1 Water Wheel — 1. Take an empty paper cup and five spoons. 2. Make five holes
around the cup and insert the spoons. 3. Then, insert a pencil or straw through the
bottom of the cup. 4. Observe that the cup moves around the pencil like a wheel. 5.
Balance your wheel on a container as shown in the image.

The paper-cup water wheel balanced on a container, as pictured on page 124.

How to build it:

1. Take an empty paper cup — a used tea cup is fine. Wipe it dry.
2. Make five small slits round the side of the cup, all at the same height and equally spaced, so
they sit like the numbers on a clock face.
3. Push one plastic spoon into each slit, with the bowl of the spoon facing outwards and all five
facing the same way round. Fix them with a little tape if they wobble.

Page 32 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

4. Make a small hole in the centre of the bottom of the cup and push a pencil or a straw
straight through it, so the pencil is the axle.
5. Spin the cup gently with your hand. Check that it turns freely round the pencil like a wheel. If
it sticks, make the hole slightly bigger.
6. Rest the two ends of the pencil on the rim of a bucket or a tub, or on two tall glasses, so the
cup hangs in the air and can turn.

Pour water here

Pencil (axle)

Wheel turns

Rest the pencil across a bucket so the cup can spin
freely.

A paper cup with five spoons round it, spinning on a pencil — a home-made water wheel.

What you observe at step 4: the cup does turn freely around the pencil, exactly like a wheel on
an axle. That is the test that your wheel is ready.

Do it over a bucket or outside. There will be splashes. And use a straw rather than
a pencil if the cup is small — it is lighter, so the wheel turns more easily.

Q2 6. Now, pour water onto your wheel. 7. Does the water make the wheel move?

Yes. The moment the falling water hits the spoons, the wheel starts to turn. Pour a thin
stream and it turns slowly. Pour a thicker, faster stream and it spins quickly. Stop pouring and
the wheel slows and stops.
How to pour:

Page 33 of 54

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

1. Fill a mug or a bottle with water.
co m
2. Hold it above one side of the wheel — not over the middle.
e m.
m l as
.co a g
3. Pour a steady stream so it lands inside the bowls of the spoons.

se m
a
4. Watch the wheel. Then pour from higher up and watch again.

g l
aHOW I POUR WHAT THE WHEEL DOES

co m
A slow trickle
m .
Turns slowly, and sometimes stops
e ag
g l as
a
A steady stream Turns smoothly, round and round

m
From higher up Turns faster — the water arrives with a harder push

Hardly turns; the push must land on the spoons atm . c o
Over the centre of the wheel
m a s e the side

e m . co agl
as
Stop pouring Slows down and stops

a g l
Why it happens: Falling water has energy because it is moving. When it lands in the

om a s
. c agl
bowl of a spoon it pushes that spoon down. The next spoon comes round, gets

s e
pushed in its turn, and so the wheel mkeeps turning. The energy of the moving water
a
agl wheel. So flowing water is a source of energy.
has become the turning of the

co m
The real thing: In hilly areas, watermills called gharaats use flowing water to grind
m .
m l a se
grain — a big wooden wheel in a stream turns a grinding stone, with no fuel and no
o
.c a g wheel called a turbine,
m
electricity. In a hydro power station, falling water spins a big
aseand that makes electricity for whole cities. Your paper cup works on the same idea.
agl
se m
com g l a
m . a
ase
Think — Page 125
Drying in the sunlight
agl
m
THINK

. co
em
m l as
.co g
Have you ever seen papads being dried in the sunlight and clothes hung out to dry?
a
Q1

a s em
agl ANSWER
.c
Yes. Almost every home in India dries things in the Sun. Papads are laid out on a sheet on the
s e m
com a
. agl
terrace, and washed clothes are hung on a line in the courtyard.

a s em or a wet shirt in the Sun.
Here is what happens to a wet papad
l water in it.
aghas
1. The papad or the cloth
2. Sunlight falls on it and warms it.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

3. The heat turns the water into water vapour — water in the form of an invisible gas.
4. The vapour mixes into the air and floats away.
5. Only the dry papad, or the dry cloth, is left behind.

Other things Indian families dry in the Sun:

WHAT IS DRIED WHY IT IS DRIED

Papads, badis, vadiyan So they become crisp and keep for months

Washed clothes and bedsheets To dry them, and the Sun also kills germs and takes away the damp
smell

Mango slices for aam papad, To store the fruit long after the mango season is over
amchur

Red chillies, turmeric, coriander Dry spices can be ground and stored
seed

Grain after the harvest Damp grain rots; dry grain keeps safely in a sack

Cow-dung cakes Dry cakes burn well as fuel

Sea water in salt pans The water goes and the salt is left behind

Why this belongs in a chapter on energy: Drying needs heat, and heat is energy.
In all these examples the energy is coming free from the Sun. No gas, no electricity,
no smoke — and nothing to pay. That is why the book calls the Sun the main source
of energy for life on Earth.

Write — Page 125
More uses of the Sun, wind and flowing water

WRITE

Q1 Can you think of more examples where we use the Sun, the wind or the flowing
water?

Yes — many. Here is a list you can copy and add to from your own village or town.

Page 35 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

SOURCE HOW WE USE IT

The Sun Drying clothes, papads, grain, chillies and mango slices

Cooking in a solar cooker

Heating water in a solar water heater on the roof

Making electricity with solar panels — on a roof, a street light, a school

Lighting our rooms in the daytime, so no bulb is needed

Helping plants make their food, and making salt in salt pans

The wind Flying kites, and turning a paper pinwheel

Winnowing — dropping grain in the breeze so the light husk blows away

Sailing boats and fishing boats with sails

Windmills that make electricity, and wind pumps that draw up water

Cooling us on a hot day, and drying clothes faster on the line

Flowing water Gharaats — hill watermills that grind grain

Hydro power stations at dams that make electricity for cities

Canal water flowing by itself into the fields

Rafts and boats carried downstream by the current

What is common to all of them: not one of these needs a plug, a cylinder or a tank
of petrol. The Sun rises again tomorrow, the wind blows again, and the river keeps
flowing. These sources come back on their own — which is why they are so valuable.

Look at the picture on page 126. It shows all three in one place: clothes drying and
a solar cooker cooking (Sun); a sailboat, a kite and a haystack in the breeze (wind); a
water wheel lifting water and a watermill turning (flowing water).

In-text Question — Page 127

Page 36 of 54

Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Vehicles that run on electricity

Q1 Did you know that even our vehicles can run on electricity?

Yes. Electric vehicles do not use petrol or diesel at all. They carry a large battery, and the
battery is charged from an electric point, just as we charge a mobile phone.
How an electric vehicle works, in four steps:

1. The vehicle is plugged into a charging point for some hours.
2. Electricity goes into its battery and is stored there.
3. When the vehicle is driven, the battery sends that stored electricity to a motor.
4. The motor turns the wheels — and the vehicle moves.

PETROL OR DIESEL VEHICLE ELECTRIC VEHICLE

What it uses Petrol or diesel Electricity stored in a battery

Smoke Gives out smoke from a pipe at the back No smoke pipe at all

Sound The engine is noisy Almost silent

Filling up A few minutes at a petrol pump Several hours at a charging point

You may already have seen some: e-rickshaws in many Indian towns, electric city buses, electric
scooters, and the metro train — which has run on electricity for years.

Why it matters: An electric vehicle makes no smoke on the road, so the air in our
streets stays cleaner. It is cleanest of all when the electricity that charges it was itself
made from the Sun, the wind or water. Look at the opening picture of this chapter on
page 114 — a red car is plugged in at a charging station, with solar panels and a
windmill in the same picture.

Write — Page 127

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Energy All Around Us — the village picture

WRITE

Q1 Energy All Around Us — List actions that you see in the picture above and fill in the
following table.

The village picture on page 127 — redrawn.

ACTIVITY SOURCE OF ENERGY

A child carrying a school bag. Food

Look carefully at the big village picture on page 127. There are fields and a canal on the left, a
road with vehicles, a village path, houses with a solar panel on one roof, and windmills far away
on the hill. Here is the table filled in. Row 1 is the book's example.

Page 38 of 54

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ACTIVITY SOURCE OF ENERGY

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A car and a scooter running on the road Fuel — petrol or diesel

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Activity 9 — Page 128
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Energy Flow Game

ACTIVITY

Q1 Energy Flow Game — Prepare paper slips with names or pictures of energy sources:
the Sun, wind, water, food, fuel and electricity. The second paper slips should
indicate types of energy, like heat, light, movement and sound. The last paper slips
should contain the uses or examples of where this energy is used — drying clothes,
lighting a bulb, turning a turbine, cooking, running, etc.

You need three sets of slips. Make them in three different colours so nobody gets confused.

SET WHAT GOES ON WRITE THESE
THE SLIPS

Set 1 — Source Where the energy Sun · Wind · Water · Food · Fuel · Electricity
(say, yellow slips) comes from

Set 2 — Type (say, What form the Heat · Light · Movement · Sound
blue slips) energy takes

Set 3 — Use (say, What that energy Drying clothes · Lighting a bulb · Turning a turbine · Cooking
green slips) actually does for us food · Running · Helping plants grow · Moving a car · Ringing
a bell

How to prepare them:

1. Cut old paper or card into slips about the size of your palm.
2. Write one word or draw one picture on each slip, in big letters.
3. Make sure the numbers work out: for every source slip there must be a matching type slip
and a matching use slip, so that every child finds a group of three.
4. Shuffle all the slips together and hand out one to each student.

Tip for the teacher or the group leader: Plan the chains on a sheet of paper first.
Then make the slips from that plan. If some children are left over, let them be the
judges who check whether each chain makes sense.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Q2 Step 1: Assigning a Role — Give each student one card, where they will either be a
source of energy, a type of energy, or a use. Step 2: Walk Around and Find Your
Match — Students should walk around the class trying to find the two others who
complete their energy chain. Step 3: Present to Class — Once matched (source —
type — use), each group should quickly explain their match to the class.

How to play, step by step:

1. Every student takes one slip and reads it quietly. Do not show it around yet.
2. All students stand up and walk about the class, saying their own word aloud — “Sun!”,
“Heat!”, “Drying clothes!”
3. Each student looks for the two others who complete the chain: one source, one type, one
use.
4. When three students think they belong together, they stand side by side in the right order —
source first, then type, then use.
5. Each group says its chain out loud to the class, in one sentence: “We are the heat of the Sun
and we help to dry clothes.”
6. The class checks the chain. If it does not make sense, the group breaks up and hunts again.

SOURCE TYPE USE
Sun Heat Drying clothes

Every chain must read in this order: where it comes from →
what it is → what it does.

One completed energy chain. Every group of three should make a sentence like this.

All the chains that work. The first two are the book's own examples.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

SOURCE TYPE OF USE THE SENTENCE TO SAY
ENERGY

Sun Heat Drying clothes “We are the heat of the Sun and we help to
dry clothes.”

Wind Movement Turning a turbine to “We are the movement of the wind and we
make electricity turn a turbine.”

Sun Light Helping plants grow “We are the light of the Sun and we help
plants make their food.”

Food Movement Running in the “We are the energy of food and we help a
playground child run.”

Fuel Heat Cooking food “We are the heat of burning gas and we
cook the dal.”

Fuel Movement Moving a car “We are the energy of petrol and we move
the car.”

Electricity Light Lighting a bulb “We are electricity turned into light and we
light the bulb.”

Electricity Sound Ringing the school bell “We are electricity turned into sound and
we ring the bell.”

Water Movement Turning a gharaat to “We are the movement of flowing water
grind grain and we grind the grain.”

What the game teaches: Energy is never just sitting still — it travels. It starts at a
source, it appears as some type (heat, light, movement or sound), and it ends up
doing a use for us. Once you can see that chain, you can explain almost anything
around you: a fan, a bus, a bulb, a boiling pot, even your own running feet.

Let us reflect — Page 130

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Closing questions

LET US REFLECT

Q1 What will happen if there is no electricity in your house for a day?

The whole day's routine would change. Nothing that runs on a wire would work — no fan,
no lights after dark, no fridge, no water pump, no TV, no charged phone.

TIME OF WHAT WOULD HAPPEN
DAY

Early morning No alarm on the phone. The water pump cannot fill the tank, so we must fetch water by hand.

Breakfast The fridge is off and yesterday's milk starts to turn. No mixer — the chutney is ground on a
stone.

Getting ready No iron for the uniform. No geyser, so a cold bath.

Daytime The rooms get hot with no fan. We open the windows and sit where there is a breeze.

Evening Homework must be finished before it gets dark, or done by a diya, a candle or a torch.

Night The house is dark and hot. The family sits outside or on the terrace. Everyone sleeps early.

Why one thing going missing changes so much: Electricity is not one machine. It
is the energy behind almost every machine in the house. So when it goes, light,
movement, cooling and sound all go together.

And what would still work: the gas stove, a bicycle, a hand fan, a matka of cool
water, the sunlight in the daytime and a bucket of water drawn by hand. Some of
these are the very old ways our grandparents used — and they still work perfectly.

Q2 Why is it better to use solar or wind energy instead of coal?

Because solar and wind energy do not pollute the air, and they never run out. Coal makes
a lot of smoke and harmful gases, and one day it will be finished.

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Q3 Give two examples where you have seen energy being stored.

Two clear examples: a battery, and our own body.

1. A battery. A torch cell, a mobile phone battery or the battery of an e-rickshaw holds energy
inside it. Nothing happens until you switch on. Then the stored energy comes out and the
torch lights, the phone rings, the rickshaw moves. When the store is finished, the battery
must be charged or changed.
2. Our own body. We eat now and the body keeps some of that energy for later. That is why we
can still walk and run even if we miss one meal — the body is spending what it saved.

Other everyday stores of energy you can add:

WHERE THE ENERGY IS STORED HOW YOU CAN TELL

A cylinder of cooking gas It does nothing while it stands there — until the burner is lit

Petrol in a scooter's tank The scooter can run for many kilometres on one fill

Firewood, coal, a diya full of oil Each one waits quietly until it is lit

A stretched rubber band or a wound-up toy Let it go and it moves by itself

Water held high up behind a dam Open the gate and the falling water spins the turbines

Grain in a store, and fat in our body Food energy kept for the months ahead

What "stored" means here: The energy is present but not being used yet. It sits
quietly and waits. When we want it, we let it out — by switching on, by lighting it, by
letting go. That is very useful, because the Sun is not always shining and we are not
always eating, but a store is always ready.

Q4 What is the one thing you can do at home to save energy?

The one thing I can do is switch off every light and fan when I leave a room. It costs
nothing, it takes one second, and it saves electricity every single day.
Sample answer: “In my house I have made it my own job. Whenever I leave a room I look back
at the switchboard before I step out. If the fan or the light is on and nobody is there, I switch it
off. I also check all the rooms once before we go out anywhere. In one month our electricity bill
came down, and my father said it was because of my checking.”

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Other good things to do, if you want to add more:

WHAT TO DO WHY IT SAVES ENERGY

Change old bulbs to LED bulbs Same light, far less electricity — that is energy efficiency

Open the curtains in the daytime Free sunlight instead of a burning bulb

Do not stand with the fridge door open Every time it is open, the fridge must work harder to cool again

Cover the pan while cooking The food cooks faster, so less gas is burnt

Dry clothes in the Sun, not in a machine The Sun does the same work for free

Unplug the charger when the phone is full A plugged-in charger keeps drawing a little electricity

Walk or cycle for short trips Saves petrol and keeps the air clean

Why small habits matter so much: One fan left on all day does not seem like much.
But one fan, in every room, in every house, every day, adds up to an enormous
amount of coal burnt somewhere far away. Saving energy at home is really about
keeping that coal in the ground and that smoke out of the air.

Q5 Find out how many kilometres a vehicle travels per litre of petrol or diesel. Ask
about different vehicles. How will you compare them?

Ask the owner or the driver: “How many kilometres does it give in one litre?” That number
is called the mileage. To compare vehicles, simply put their mileage numbers side by side
— the one that gives more kilometres per litre uses less fuel for the same journey.
How to find out:

1. Choose four or five vehicles you can actually ask about — the family scooter, a neighbour's
car, an auto, the school bus, a tractor.
2. Ask the owner two things: how many litres of fuel go in, and how far the vehicle runs on that.
3. Work out the kilometres for one litre by dividing.
4. Write the answers in a table.

Mileage = distance travelled ÷ litres of fuel used

Example: a scooter goes 200 km on 4 litres.

200 ÷ 4 = 50 km in 1 litre

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Sample answer — what my table looked like:

VEHICLE FUEL KILOMETRES IN 1 FUEL NEEDED FOR A 100 KM
LITRE TRIP

Motorcycle Petrol about 60 km 100 ÷ 60 ≈ 1.7 litres

Scooter Petrol about 50 km 100 ÷ 50 = 2 litres

Small car Petrol about 18 km 100 ÷ 18 ≈ 5.6 litres

Auto- CNG / about 25 km 100 ÷ 25 = 4 litres
rickshaw petrol

Bus Diesel about 5 km 100 ÷ 5 = 20 litres

These are only sample figures. Write the real numbers you are told.
How to compare them fairly. Three fair ways:

1. Kilometres per litre. Bigger is better. The motorcycle wins.
2. Fuel for the same journey. Fix a distance, say 100 km, and work out the litres each vehicle
needs. Smaller is better.
3. Fuel per person. This is the fairest of all. A bus gives only 5 km per litre, but it carries 50
people. Work it out: for 100 km the bus needs 20 litres, so that is 20 ÷ 50 = 0.4 litre for each
person. The car needs 5.6 litres and carries perhaps 4 people, so that is 5.6 ÷ 4 = 1.4 litres
for each person. So the bus is more than three times better per person.

Why the third way is the right one: A vehicle is not made to move itself — it is
made to move people. So the honest question is not “how much fuel per kilometre”
but “how much fuel per person per kilometre”. That is exactly why a full bus, a
shared auto or a metro train saves so much more fuel than everyone driving alone.

Compare fairly: only compare vehicles doing similar work, and remember that
mileage changes with the load, the road, the traffic and how well the vehicle is
looked after.

Q6 Look around your home or classroom. List any three objects that use energy and
mention their source of energy. For example: Object; Fan → Energy Source:
Electricity

Here are three, written the way the book shows. The first is the book's own example.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Object: Fan → Energy Source: Electricity

Object: Gas stove → Energy Source: LPG cooking gas (a fuel)

Object: Torch → Energy Source: The stored energy in its battery

Many more, if you want to make a longer list:

OBJECT SOURCE OF ENERGY

Tube light, television, fridge, mixer, water pump Electricity

Diya, lantern Oil or kerosene (a fuel)

Chulha Firewood (a fuel)

Scooter, car, school bus Petrol or diesel (a fuel)

Wall clock, TV remote A cell — stored energy

Bicycle, skipping rope, cricket bat Food — the energy of the person using it

Solar street light, solar water heater The Sun

Clothes line, pinwheel The Sun and the wind

How to check your own list: ask two questions about each object. First, “What is it
doing?” — moving, lighting, sounding, heating or cooling. Second, “What would
make it stop?” — a power cut, an empty tank, a dead cell, or a hungry person.
Whatever would make it stop is its source of energy.

Q7 7. Create and share: (a) Draw or make a simple plan of a ‘clean energy home’ that
uses solar, wind or any such source of energy.

A clean energy home does three things: it makes its own clean energy, it uses as little
energy as it can, and it uses the Sun and the breeze directly instead of machines.
Sample answer — my clean energy home
1. Making our own clean energy

Solar panels on the roof, facing the Sun, making electricity for the lights, the fan and the TV.
A solar water heater on the roof, so no geyser is needed.
A solar cooker in the courtyard for rice, dal and vegetables on sunny days.

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A small windmill on the terrace to add electricity on windy days.
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A solar street light at the gate that charges all day and lights up by itself at night.
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3. Keeping the house comfortable without machines

Thick walls and a shaded verandah, so the rooms stay cool in summer and warm in winter

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— the way traditional Indian houses were built.
Windows on two opposite walls, so the breeze blows right through.
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Trees on the sunny side for shade, and a courtyard in the middle for light and air. This is

a s emVaastu Shastra has always advised — placing rooms, doors and windows to make the
what

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A rainwater pipe from the roof to a tank, so the pump runs less.

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How to draw it well: Draw a big simple side view of the house. Then label every part
with an arrow — “solar panel”, “solar water heater”, “LED bulb”, “clothes line”, “shade
tree”, “window for the breeze”. Neat labels matter far more than a beautiful drawing.
Put a short line at the bottom saying what your home saves.

Q8 7. Create and share: (b) Make ‘my energy diary’ for one day, record the number of
times you have used the electricity fuel and so on.

An energy diary is a record of every time you used energy in one day. Keep a small
notebook with you and make a mark each time. At the end of the day, count.
How to make it:

1. Rule three columns in your notebook: Time, What I did, Source of energy.
2. Write a line every time you switch something on, ride in something, or eat something.
3. At the end of the day, count how many times each source was used.
4. Write one line at the bottom: what will I change tomorrow?

Sample answer — My Energy Diary, Monday

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

TIME WHAT I DID SOURCE OF ENERGY

6:30 a.m. Switched on the light in my room Electricity

6:45 a.m. Bath with water heated on the stove Fuel — cooking gas

7:15 a.m. Ate paratha and drank milk Food

7:40 a.m. Walked to school Food

8:00 a.m. Class fan and lights on all morning Electricity

1:30 p.m. Came home in the school bus Fuel — diesel

2:00 p.m. Lunch cooked on the gas stove Fuel — cooking gas

4:00 p.m. Played cricket in the ground Food

5:30 p.m. Took clothes off the line — dried by themselves The Sun and the wind

6:30 p.m. Homework under the tube light, fan on Electricity

8:00 p.m. Watched TV for half an hour Electricity

9:00 p.m. Charged the phone Electricity

My count for the day

SOURCE OF ENERGY NUMBER OF TIMES

Electricity 6

Fuel (gas, diesel) 3

Food 3

Sun and wind 1

Total 13 times in one day

What I learnt, and what I will change: I used electricity more than anything else — six times
out of thirteen. Two of those were not really needed: the fan stayed on in my room after I left it,
and the tube light burned in the afternoon when there was plenty of daylight. Tomorrow I will
switch off before leaving the room and open the curtains instead of the light. And I will try to
walk to more places, because walking runs on food and makes no smoke at all.

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Why keeping a diary works: Most energy is not wasted on purpose — it is wasted
without noticing. Writing it down forces you to notice. Once you can see the count
on paper, you can see exactly which two or three habits to change, and that is where
saving really begins.

Chapter at a glance
Energy is what makes things happen. Look at the kitchen picture on page 114. The food is
cooking. The knife is cutting. Sunlight is coming in through the window. Something must be
making each of these things happen. That something is energy. We cannot see energy
itself. We only see what it does.
Energy does five kinds of jobs. The book lists them on page 115 — energy makes things
move, gives light, makes sound, makes things hot, and makes things cool. So the book's
own definition is: energy is what makes things move, light up, produce sound, do work and
change temperature.
Food is the energy source for every living thing. When we are hungry we feel tired. After
we eat we feel active and ready to play. That is because food gives us energy. A dog
running, a bird flying, a fish swimming — every animal gets its energy from food too. Even
when we sit quietly, or sleep, our brain keeps using energy.
Fuel is what a machine 'eats'. Petrol and diesel are the fuels that run cars and scooters. At
home, LPG cooking gas is a fuel. In some places people cook with wood or coal. Oil in a diya
is a fuel too — Activity 4 shows that the diya with oil keeps burning while the dry one goes
out. But burning wood and coal makes smoke and dirty gases, so they must be used
carefully.
Electricity runs most of the machines around us. A fan moves air, a bulb gives light, a
radio makes sound, a heater makes heat, a fridge makes things cool. So electricity can do all
five jobs of energy. Factories run their machines on electricity too, and that is how our
clothes, books, toys and vehicles get made. Electricity is very useful but it can hurt us, so
never touch bare wires, never put anything into a socket, stay away from broken wires and
transformers, and always call an adult.
Most of our electricity is made by burning coal — and that pollutes. Burning coal gives
a lot of smoke and harmful gases. That dirty air is bad for our health and bad for the Earth.
So we look for sources that do not pollute.
The Sun, the wind and flowing water are sources of energy. Three activities in the
chapter prove it. A paper pinwheel spins in the wind. A magnifying glass gathers sunlight
into one hot spot and scorches paper. A paper-cup wheel with spoons turns when water is
poured on it. In the same way, solar panels turn sunlight into electricity, windmills turn
with the wind to make electricity, and fast rivers or falling water make electricity too.
Electricity from the Sun, wind and water is called clean energy. It does not fill the air
with smoke or leave waste behind. India uses a lot of it — the Bhadla Solar Park in

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Class 5 The World Around Us Chapter 7 Energy—How Things Work AglaSem · NCERT Solutions

Rajasthan is one of the largest solar power plants in the world, and Cochin International
Airport in Kerala was the first airport in the world to run fully on solar energy. Using less
energy for the same work is called energy efficiency; an LED bulb gives the same light as
an old bulb but uses far less electricity.
Energy can be stored, and it should be saved. Our body stores energy, which is why we
can still run even if we miss a meal. A torch battery stores energy too. People in India have
always used energy cleverly — sails on old trading ships, gharaats (watermills) turning on
hill streams, thick walls and small windows to keep a house cool, cattle kept on the ground
floor to warm the rooms above in Himachal Pradesh, Uttarakhand and Ladakh, and Vaastu
Shastra placing doors and windows to make the best use of sunlight and breeze.

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