Measurement of Time and Motion - Class 7 Science (CBSE)

Based on the 2026-27 Class 7 Science syllabus for the NCERT-aligned book Curiosity. Use these notes to understand, observe, explain, and answer in full sentences.

1. Why this chapter matters

Motion becomes scientific when it is measured. Time, distance, speed, and graphs help us describe whether something is slow, fast, uniform, or changing.

This chapter is not meant for rote learning. Read every idea with an example, then ask: what can I observe, test, draw, measure, or explain?

2. Core ideas

Measuring time

Humans have used natural cycles, sundials, water clocks, pendulums, and modern clocks to measure time. The SI unit of time is second.

Simple pendulum

A simple pendulum has a bob suspended by a string. Its time period is the time for one complete oscillation and mainly depends on length.

Speed

Speed tells distance covered per unit time. It is calculated as distance divided by time.

3. Key points to remember

• Speed: speed = distance / time.
• SI unit of time: second.
• Uniform motion: Equal distances in equal time intervals.
• Time period: Time for one complete oscillation.

4. Worked examples

Example 1: A cyclist covers 120 m in 20 s. Find speed.

Speed = distance/time = 120/20 = 6 m/s.

Example 2: A train travels 180 km in 3 h. Find speed.

Speed = 180/3 = 60 km/h.

Example 3: What is uniform motion?

Motion in which equal distances are covered in equal time intervals.

Example 4: What happens to pendulum time period when length increases?

The time period increases.

5. Activity and observation

Measure how long 20 oscillations of a pendulum take, then divide by 20 to estimate one time period. Repeat for different lengths.

Write the activity in this format:

• Aim: What are you trying to find out?
• Materials: What did you use?
• Procedure: What steps did you follow?
• Observation: What did you see or measure?
• Conclusion: What scientific idea does it prove?

6. Common mistakes

• Writing only definitions without examples.
• Drawing diagrams without labels.
• Confusing observation with conclusion.
• Ignoring units in speed, time, distance, temperature, or measurement questions.
• Giving unsafe suggestions for experiments instead of classroom-safe methods.

7. Practice set

1. Define the main idea of Measurement of Time and Motion.
2. Write two key terms from this chapter and explain them.
3. Describe one activity that proves an idea from this chapter.
4. Give one real-life application of time measurement.
5. Write one difference-based question from this chapter.
6. How can you make your answer more scientific?

8. Answer key

1. Define the main idea of Measurement of Time and Motion. Answer: Motion becomes scientific when it is measured. Time, distance, speed, and graphs help us describe whether something is slow, fast, uniform, or changing.

2. Write two key terms from this chapter and explain them. Answer: time measurement and simple pendulum are central terms. Define each with one example from daily life.

3. Describe one activity that proves an idea from this chapter. Answer: Measure how long 20 oscillations of a pendulum take, then divide by 20 to estimate one time period. Repeat for different lengths.

4. Give one real-life application of time measurement. Answer: Use the chapter idea to explain a daily event, then name the observation that supports your answer.

5. Write one difference-based question from this chapter. Answer: Compare two related ideas, such as Measuring time and Simple pendulum, using meaning and example.

6. How can you make your answer more scientific? Answer: Use observation, correct vocabulary, labelled diagrams or tables, and a clear reason.

9. Quick revision

• Main themes: time measurement, simple pendulum, speed, uniform motion, distance-time data.
• Learn definitions with examples.
• Practise one diagram, table, or activity.
• Revise the worked examples.
• Write answers using cause, evidence, and conclusion.