NCERT Book Class 7 Science Chapter 9 Motion and Time

9 Motion and Time

I
n Class VI, you learnt about different 9.1 SLOW OR FAST
types of motions. You learnt that a We know that some vehicles move faster
motion could be along a straight line, than others. Even the same vehicle may
it could be circular or periodic. Can you move faster or slower at different times.
recall these three types of motions? Make a list of ten objects moving along
Table 9.1 gives some common a straight path. Group the motion of
examples of motions. Identify the type these objects as slow and fast. How did
of motion in each case. you decide which object is moving slow
Table 9.1 Some examples of and which one is moving fast?
different types of motion If vehicles are moving on a road in
Example of Type of motion the same direction, we can easily tell
which one of them is moving faster than
motion Along a straight
line/circular/ the other. Let us look at the motion of
periodic vehicles moving on a road.
Soldiers in a Activity 9.1
march past
Look at Fig. 9.1. It shows the position
Bullock cart of some vehicles moving on a road in
moving on a the same direction at some instant of
straight road time. Now look at Fig. 9.2. It shows the
Hands of an position of the same vehicles after some
athlete in a race time. From your observation of the two
Pedal of a bicycle figures, answer the following questions:
in motion Which vehicle is moving the fastest
Motion of the Earth of all? Which one of them is moving the
around the Sun
slowest of all?
The distance moved by objects in a
Motion of a swing
given interval of time can help us to
Motion of a decide which one is faster or slower. For
pendulum example, imagine that you have gone to
It is common experience that the see off your friend at the bus stand.
motion of some objects is slow while that Suppose you start pedalling your bicycle
of some others is fast. at the same time as the bus begins to