Extra Questions for Class 7 Science Chapter 8: Measurement of Time and Motion

Fresh practice questions for Class 7 Science Chapter 8 “Measurement of Time and Motion”, reinforcing speed calculations and motion concepts. These Class 7 Science Chapter 8 important questions are handy for last-minute exam practice.

Last Updated: September 23, 2026

Q1. A cyclist covers 300 m in 25 seconds. Find the cyclist's speed in both m/s and km/h.

Answer: Speed = 300/25 = 12 m/s. In km/h: 12 × 18/5 = 43.2 km/h

Q2. Assertion-Reason — Assertion (A): A car moving through a busy market at varying speeds is in non-uniform…

Assertion (A): A car moving through a busy market at varying speeds is in non-uniform motion.
Reason (R): Non-uniform motion means the object covers unequal distances in equal time intervals.

Answer: Both A and R are true, and R correctly explains A.

Q3. Convert a speed of 90 km/h into m/s.

Answer: 90 × 5/18 = 25 m/s

Q4. Spot the error — A student says: "Since two runners finish a 200m race in different times, we can't tell…

A student says: “Since two runners finish a 200m race in different times, we can’t tell who was faster without knowing their speeds.” Identify the error.

Answer: This statement is actually incorrect reasoning to flag as an error to fix: for races of the same distance, the runner with the shorter time is automatically the faster one – there’s no need to calculate speed separately, since time and speed are inversely related when distance is fixed.

Q5. HOTS — Two cars start from the same point. Car A travels at a constant 60 km/h. Car B…

Two cars start from the same point. Car A travels at a constant 60 km/h. Car B alternates between 80 km/h and 40 km/h every hour. After 2 hours, which car has travelled further, and is either car in uniform motion?

Answer: Car A: 60×2=120 km (uniform motion, constant speed). Car B: 80+40=120 km over 2 hours (non-uniform motion, since its speed changes). Both cars travel the same total distance (120 km), but only Car A is in uniform motion.

Q6. A runner's average speed over a 10 km race is 12 km/h. How long did the race take?

Answer: Time = Distance/Speed = 10/12 = 5/6 hour = 50 minutes

Q7. Explain why a candle clock or water clock would be less accurate for measuring time than a modern digital clock.

Answer: Candle clocks and water clocks depend on physical processes (wax burning at a roughly constant rate, or water dripping at a roughly constant rate) that can be affected by external factors like temperature, wind, humidity, or the exact size of the opening, making them far less precise and consistent than a digital clock, which uses a highly stable electronic oscillator to measure time.

Q8. A train covers the first 100 km in 1 hour and the next 100 km in 1.5 hours. Is this uniform motion? Find its average speed for the full 200 km.

Answer: Since the train takes different times to cover equal distances, this is non-uniform motion. Total time = 1+1.5 = 2.5 hours. Average speed = 200/2.5 = 80 km/h.

Q9. If light travels at approximately 300,000 km/s, how long does it take light to travel 1,500,000 km?

Answer: Time = Distance/Speed = 1,500,000/300,000 = 5 seconds

Q10. A walker moves 4 km in the first hour, 4 km in the second hour, and 4 km in the third hour. Classify this motion and explain your reasoning.

Answer: This is uniform motion, since the walker covers equal distances (4 km) in each equal time interval (1 hour), meaning their speed remains constant throughout.

NCERT Solutions: Class 7 Science Chapter 8

Revision Notes: Class 7 Science Chapter 8 Revision Notes

Frequently Asked Questions

If a car travels 150 kilometres in 3 hours, what is its average speed?
Average speed is calculated by dividing total distance by total time taken, so dividing 150 kilometres by 3 hours gives an average speed of 50 kilometres per hour.

Why might the actual speed of a moving object differ from its calculated average speed at various points during a journey?
Average speed only accounts for overall distance and total time, so an object might travel faster during some parts of the journey and slower during others, differing from the calculated average.

Written by Satish

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