Chapter: 4 – Describing Motion Around Us
Maximum Marks: 50
Suggested Time: 1 Hour 30 Minutes
This Class 9 Science Exploration Chapter 4 Sample Paper 1 is designed to help students practise important concepts from “Describing Motion Around Us.” The 50-mark paper covers rest and motion, distance and displacement, speed and velocity, uniform and non-uniform motion, acceleration, motion graphs, and basic numerical problems. The paper includes objective, short-answer, application-based, and numerical questions, followed by complete solutions for effective revision and self-assessment.
Sample Paper 1
General Instructions
- All questions are compulsory.
- Read each question carefully before answering.
- Show all necessary steps in numerical problems.
- Use SI units wherever applicable.
- Draw neat and labelled graphs wherever required.
- Take appropriate assumptions wherever necessary.
Section A — Objective Questions
10 × 1 = 10 Marks
Q1. Which of the following is a scalar quantity?
a) Displacement
b) Velocity
c) Speed
d) Acceleration
Q2. The total length of the actual path travelled by an object is called:
a) Displacement
b) Distance
c) Velocity
d) Acceleration
Q3. Which quantity describes the change in position of an object in a specified direction?
a) Distance
b) Speed
c) Displacement
d) Time
Q4. The SI unit of speed is:
a) km/h
b) m/s
c) m
d) m/s²
Q5. If an object covers equal distances in equal intervals of time, its motion is called:
a) Random motion
b) Uniform motion
c) Accelerated motion
d) Circular motion
Q6. Which quantity tells us how quickly velocity changes with time?
a) Speed
b) Distance
c) Acceleration
d) Displacement
Q7. An object moving with constant velocity has:
a) Increasing acceleration
b) Zero acceleration
c) Constant positive acceleration
d) Variable speed
Q8. The slope of a distance-time graph represents:
a) Acceleration
b) Speed
c) Displacement
d) Force
Q9. A body travels 100 m in 20 s. Its average speed is:
a) 2 m/s
b) 5 m/s
c) 20 m/s
d) 2000 m/s
Q10. Which of the following can be zero even when an object has travelled a non-zero distance?
a) Distance
b) Speed
c) Displacement
d) Time
Section B — Very Short Answer Questions
5 × 2 = 10 Marks
Q11. Define rest and motion.
Q12. Give two differences between distance and displacement.
Q13. What is average speed? Write its formula.
Q14. Define velocity and state how it differs from speed.
Q15. What is acceleration? Write its SI unit.
Section C — Short Answer and Numerical Questions
4 × 3 = 12 Marks
Q16. A student walks 300 m in 5 minutes. Calculate the student’s average speed in m/s.
Q17. Explain the difference between uniform and non-uniform motion with one example of each.
Q18. A car starts from rest and reaches a velocity of 20 m/s in 5 seconds. Calculate its acceleration.
Q19. Explain why a person sitting inside a moving bus can be considered at rest with respect to another passenger but in motion with respect to a person standing on the road.
Section D — Application-Based and Numerical Questions
2 × 4 = 8 Marks
Q20. A cyclist travels 2 km east and then 2 km west, returning to the starting point.
Answer the following:
a) What is the total distance travelled?
b) What is the final displacement?
c) Is the distance zero?
d) Is the displacement zero? Explain briefly.
Q21. The velocity of a car changes from 10 m/s to 25 m/s in 5 seconds.
a) What is the initial velocity?
b) What is the final velocity?
c) Calculate the acceleration.
d) Is the car accelerating or decelerating?
Section E — Long Answer and Numerical Questions
2 × 5 = 10 Marks
Q22. Explain distance, displacement, speed and velocity. Give the SI unit of each and state whether each quantity is scalar or vector.
Q23. A train starts from rest and accelerates uniformly at 2 m/s² for 10 seconds.
Calculate:
a) Its final velocity.
b) The distance travelled during these 10 seconds.
Use the appropriate equations of motion and show all steps.
SOLUTIONS
Section A — Answers
Q1. c) Speed
Q2. b) Distance
Q3. c) Displacement
Q4. b) m/s
Q5. b) Uniform motion
Q6. c) Acceleration
Q7. b) Zero acceleration
Q8. b) Speed
Q9. b) 5 m/s
Q10. c) Displacement
Section B — Solutions
Q11. Rest and Motion
An object is said to be at rest when its position does not change with respect to a chosen reference point over time.
An object is said to be in motion when its position changes with respect to a chosen reference point over time.
Therefore, rest and motion are relative to the reference point.
Q12. Distance and Displacement
| Distance | Displacement |
|---|---|
| Total length of the actual path travelled | Shortest straight-line change in position from initial to final position |
| Scalar quantity | Vector quantity |
| Always positive or zero | Can be positive, negative or zero depending on the chosen direction |
Q13. Average Speed
Average speed is the total distance travelled divided by the total time taken. Average Speed=Total TimeTotal Distance
Its SI unit is m/s.
Q14. Velocity
Velocity is the rate of change of displacement with time. Velocity=TimeDisplacement
Speed tells us how fast an object moves, while velocity also includes the direction of motion.
Q15. Acceleration
Acceleration is the rate of change of velocity with time. a=tv−u
where:
- u = initial velocity
- v = final velocity
- t = time
The SI unit of acceleration is m/s².
Section C — Solutions
Q16. Average Speed
Given:
Distance = 300 m
Time = 5 minutes
Convert time into seconds: 5×60=300 s
Average speed: Average Speed=TimeDistance =300300 1 m/s
Answer: The student’s average speed is 1 m/s.
Q17. Uniform and Non-Uniform Motion
Uniform motion:
An object is said to be in uniform motion when it covers equal distances in equal intervals of time.
Example: A train moving along a straight track at constant speed.
Non-uniform motion:
An object is in non-uniform motion when it covers unequal distances in equal intervals of time or its direction of motion changes.
Example: A car moving through a crowded road with frequent changes in speed.
Q18. Acceleration
Given:
Initial velocity, u=0 m/s
Final velocity, v=20 m/s
Time, t=5 s
Using: a=tv−u a=520−0 a=4 m/s2
Answer: The acceleration is 4 m/s².
Q19. Motion Relative to a Reference Point
Motion is described with respect to a reference point.
A passenger sitting inside a moving bus does not change position relative to another passenger sitting beside them. Therefore, the passenger is at rest with respect to the other passenger.
However, both passengers change their positions relative to a person standing on the road. Therefore, they are in motion with respect to the person on the road.
This shows that rest and motion are relative concepts.
Section D — Solutions
Q20. Cyclist’s Journey
The cyclist travels:
- 2 km east
- 2 km west
a) Total distance
Distance=2+2=4 km
Answer: 4 km
b) Final displacement
The cyclist returns to the starting point.
Therefore: Displacement=0
c) Is the distance zero?
No. The cyclist travelled a total distance of 4 km.
d) Is the displacement zero?
Yes. Since the initial and final positions are the same, the net displacement is zero.
Q21. Change in Velocity
Given:
Initial velocity: u=10 m/s
Final velocity: v=25 m/s
Time: t=5 s
a) Initial velocity
10 m/s
b) Final velocity
25 m/s
c) Acceleration
a=tv−u a=525−10 a=515 3 m/s2
d) Type of motion
The velocity increases from 10 m/s to 25 m/s.
Therefore, the car is accelerating.
Section E — Solutions
Q22. Distance, Displacement, Speed and Velocity
1. Distance
Distance is the total length of the actual path travelled by an object.
- SI unit: metre (m)
- Nature: Scalar quantity
Distance does not require a direction.
2. Displacement
Displacement is the change in position of an object from its initial position to its final position in a specified direction.
- SI unit: metre (m)
- Nature: Vector quantity
Displacement can be zero even when an object has travelled a non-zero distance.
3. Speed
Speed is the distance travelled per unit time. Speed=TimeDistance
- SI unit: m/s
- Nature: Scalar quantity
4. Velocity
Velocity is the displacement per unit time. Velocity=TimeDisplacement
- SI unit: m/s
- Nature: Vector quantity
Summary
| Quantity | Meaning | SI Unit | Type |
|---|---|---|---|
| Distance | Total path length | m | Scalar |
| Displacement | Change in position with direction | m | Vector |
| Speed | Distance per unit time | m/s | Scalar |
| Velocity | Displacement per unit time | m/s | Vector |
Q23. Motion of the Train
Given:
Initial velocity: u=0 m/s
Acceleration: a=2 m/s2
Time: t=10 s
a) Final Velocity
Using the equation: v=u+at
Substitute the values: v=0+(2)(10) v=20 m/s
Therefore, the final velocity of the train is 20 m/s.
b) Distance Travelled
Using: s=ut+21at2
Substitute the values: s=(0)(10)+21(2)(10)2 s=0+1×100 s=100 m
Therefore, the train travels 100 m in 10 seconds.
Final Answers
Final velocity = 20 m/s
Distance travelled = 100 m