NCERT Book Class 7 Science (Curiosity) Chapter 8 Measurement of Time and Motion

Measurement of
8 Time and Motion

Prerna and her younger sister are watching a sports channel
on television. Prerna enjoys running and she has been declared
the fastest runner among the girls in her district for winning
the 100 metre sprint at an interschool competition held at the
district level. She is now training to compete at the state level.
She dreams of representing India at the international level in 100
metre sprint contests in future.
While watching the rerun of sprints at the Olympic games held
in the past, Prerna is always amazed that the measurement of
the time taken for the race is so advanced that they could identify
the winner even when two sprinters seemed to cross the finish
line almost together. However, in her school, the sports teacher
only used a special kind of watch called a ‘stopwatch’ for timing
the school races. She had noticed her mother wearing a watch on
her wrist and her sister looking at her mobile phone when she
needed to check the time. Her uncle used a Braille watch and had
recently acquired a talking watch that announced the time at the
touch of a button. There was also a large clock on the wall near
the school entrance. Her thoughts turned to people in the ancient
past, who did not have the modern gadgets we have today and
she wondered…