Revision Notes for Class 7 Science Chapter 8: Measurement of Time and Motion

Quick revision notes summarizing all key concepts from Class 7 Science Chapter 8 “Measurement of Time and Motion”. These Class 7 Science Chapter 8 notes are ideal for quick revision just before exams.

Last Updated: September 23, 2026

• Before mechanical clocks, time was measured using sundials, water clocks, hourglasses, and candle clocks.
• Speed = Distance ÷ Time. It tells us how fast an object is moving, and allows fair comparison between motions covering different distances or taking different times.
• Speed unit conversion: to convert km/h to m/s, multiply by 5/18. To convert m/s to km/h, multiply by 18/5.
• Uniform motion: an object covers equal distances in equal intervals of time (constant speed).
• Non-uniform motion: an object covers unequal distances in equal intervals of time (changing speed) – this is the more common type of motion in everyday life (e.g., traffic, sports, walking through crowds).
• Average speed = Total distance travelled ÷ Total time taken. This applies even when the motion is non-uniform.
• To find a required speed for a remaining distance/time in a multi-part journey, use Speed = Remaining distance ÷ Remaining time.
• Real-world timetable data (like train schedules) can be used to calculate speed between any two points using the standard speed formula.

NCERT Solutions: Class 7 Science Chapter 8
Extra Questions: Class 7 Science Chapter 8

For the full chapter, see the Class 7 Science book page and the Class 7 Science Formulas Handbook.

Frequently Asked Questions

What is the difference between a fixed reference point and a moving reference point when describing motion?
Motion is described relative to a reference point; an object may appear stationary relative to a moving reference point like a fellow passenger on a train, while appearing to move relative to a fixed reference point outside.

How is average speed calculated, and what does it actually represent?
Average speed is calculated by dividing total distance travelled by total time taken, representing an overall rate of motion over the entire journey without describing how speed varied along the way.

Written by Satish

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