Science · Class 7
Motion and Time
Speed, distance-time graphs, and uniform circular motion.
4 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Speed = distance/time. To convert km/h to m/s, multiply by 5/18.
Motion describes change of position with time. This chapter covers uniform and non-uniform motion, speed, measurement of time, simple pendulum, and distance-time graphs.
Speed and Motion
- Speed = distance / time; SI unit m/s
- Uniform motion: equal distances in equal time
- Non-uniform: unequal distances in equal time
- Average speed = total distance / total time
Measuring Time
- Simple pendulum: periodic motion — time period depends on length, not bob mass
- Oscillation: to-and-fro from mean position
- Modern clocks: quartz, atomic clocks
Distance-Time Graph
- Straight line through origin: uniform speed
- Slope of graph = speed
- Horizontal line: object at rest
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Calculate speed
A car travels 150 km in 3 hours. Find speed in km/h and m/s.
- 1Speed = 150/3 = 50 km/h
- 250 × (5/18) ≈ 13.9 m/s
Answer
50 km/h or 13.9 m/s
Pendulum
Does pendulum period depend on bob mass?
- 1Period depends on length and gravity
- 2Mass of bob does not affect period
- 3Galileo demonstrated this
Answer
No — depends on length, not mass
Key Points to Remember
- ✓ 1 km/h = 5/18 m/s
- ✓ Odometer measures distance
- ✓ Speedometer measures instantaneous speed
Exam Tips
- • Plot distance-time graph from data table
- • Convert km/h to m/s
- • Define uniform and non-uniform motion
Practice MCQs — Motion and Time
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
SI unit of speed is: