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Class 7 Science: Measurement of Time and Motion, 8 practice questions with answers

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These are 8 practice questions on Class 7 Science Chapter 8, Measurement of Time and Motion, of the new NCERT textbook, Curiosity. Each has a worked answer and the textbook page it comes from. They cover the time period of a pendulum, writing units of time, what makes something usable as a clock, working out speed, distance and time, average speed on a trip with a rest, reading an odometer, and what uniform linear motion means. Try each one on paper before you open the answer.

These questions are our own, drafted with AI help. Every number was re-computed by a test script and none of the numbers is taken from the chapter apart from 60, the number of seconds in a minute and minutes in an hour, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity: Textbook of Science for Grade 7, Chapter 8, printed pages 105 to 120):

Measurement of time

Question 1. Ravi pulls a pendulum's bob to one extreme position, A, and lets it go. He times how long it takes to reach the other extreme position, B, as 0.85 s, and says, "The time period is 0.85 s." Find his mistake and the correct time period.

Answer: A to B is only half an oscillation; the time period is 1.7 s. One oscillation is complete only when the bob goes from A to B and comes back to A. Going from A to B takes 0.85 s, and coming back takes the same time, so the time period is 0.85 s + 0.85 s = 1.7 s. (One oscillation and the time period, page 109.)

Question 2. Neha writes in her science notebook: "The race took 37 Sec. and the bus ride took 2 Hrs." Correct the way she has written the units.

Answer: "37 s" and "2 h". The symbol for second is "s" and for hour is "h". Unit symbols are written in lowercase and in the singular, with no full stop after them (except at the end of a sentence) and with a space between the number and the unit, and writing "sec" or "hrs" is incorrect. So the sentence should read: "The race took 37 s and the bus ride took 2 h." (Writing units of time, page 111.)

Question 3. Which of these could be used to keep time: (a) a tap that drips at a steady rate, (b) a long incense stick with marks along it, (c) the number of cars passing a gate? Explain.

Answer: (a) and (b) could; (c) could not. All clocks are based on a process that repeats continuously and marks equal intervals of time. A steady drip repeats at equal intervals, so drips can be counted, like a water clock. An incense stick with marks burns down at a steady rate, like a candle clock. Cars pass a gate at irregular times, so counting them does not mark equal intervals. (Early clocks, page 106; the principle of all clocks, page 111.)

Speed

Question 4. A scooter goes 5.7 km in 19 min. Ravi works out its speed as 5.7 ÷ 19 = 0.3 m/s. Find his mistake and the correct speed in m/s.

Answer: he divided kilometres by minutes; the speed is 5 m/s. To get m/s, the distance must be in metres and the time in seconds. 5.7 km = 5,700 m and 19 min = 19 × 60 s = 1,140 s. So the speed = 5,700 m ÷ 1,140 s = 5 m/s. Ravi's 0.3 is in kilometres per minute, not in metres per second. (Speed and its units, pages 113 and 114.)

Question 5. A bus travels at 57 km/h. Kiran works out how long it takes to cover 171 km as 57 ÷ 171, which gives one-third of an hour. Find her mistake and the correct time.

Answer: she divided the speed by the distance; the time is 3 h. Time taken = distance covered ÷ speed = 171 km ÷ 57 km/h = 3 h. Kiran divided the other way round. A quick check: in 3 h at 57 km/h, the bus covers 3 × 57 = 171 km. (Distance, speed and time, page 115.)

Question 6. Meena walks 1.1 km in 19 min, rests for 5 min, then walks another 1.1 km in 9 min. She says, "My rest should not count, so my average speed is 2.2 km in 28 min." What is her average speed for the whole trip, in km/h?

Answer: 4 km/h, counting the rest. Average speed is the total distance covered divided by the total time taken, and the total time includes the rest. Total distance = 1.1 + 1.1 = 2.2 km. Total time = 19 + 5 + 9 = 33 min. In one hour (60 min) she would cover 2.2 × 60 ÷ 33 = 4 km, so her average speed is 4 km/h. (Average speed, pages 113 and 115.)

Uniform and non-uniform motion

Question 7. At the start of a car trip the odometer reads 24318 km, and at the end it reads 24411 km. The trip took one and a half hours. What was the car's average speed?

Answer: 62 km/h. The odometer shows the distance travelled, so the trip covered 24411 − 24318 = 93 km. The time was one and a half hours, 1.5 h. Average speed = 93 km ÷ 1.5 h = 62 km/h. (The odometer, page 116; average speed, pages 113 and 115.)

Question 8. Sana says, "The tip of a ceiling fan's blade, turning at a steady speed, is in uniform linear motion." Find her mistake.

Answer: the tip moves in a circle, not along a straight line, so it is not linear motion. Uniform linear motion means moving along a straight line with a constant speed. The tip of the blade may move at a steady speed, but it goes round in a circle, so its motion is not linear at all. (Linear motion, page 116; uniform linear motion, page 117.)

Questions students ask

What is the time period of a pendulum? The time it takes to complete one oscillation: from one extreme position to the other and back. For a pendulum of a given length, it stays the same at a place, which is why pendulums were used in clocks. (Pages 109 and 110.)

What is the SI unit of time, and how is it written? The second, with the symbol s; 60 s make a minute (min) and 60 min make an hour (h). The symbols are lowercase and singular, with no full stop. (Page 111.)

What do a speedometer and an odometer show? A speedometer shows a vehicle's speed in km/h. An odometer shows the distance the vehicle has travelled, in kilometres. (Page 116.)

Practise more, and check your marks

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Sources

All opened and read on 22 October 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 104.

The facts are from the textbook pages above. The questions, worked answers and checks are our own, and every number was re-computed by script. This guide is general information; follow your teacher and the textbook.