Chapter: 4 – Describing Motion Around Us
Maximum Marks: 50
Suggested Time: 1 Hour 30 Minutes

This Class 9 Science Exploration Chapter 4 Sample Paper 2 provides a fresh set of practice questions from “Describing Motion Around Us.” The paper focuses on different aspects of motion, including reference points, distance and displacement, speed and velocity, acceleration, graphical representation of motion, average speed, and equations of motion. All questions are different from Sample Paper 1, with complete solutions provided at the end.

Sample Paper 2

General Instructions

All questions are compulsory.
Read each question carefully.
Show all steps in numerical problems.
Use SI units wherever applicable.
Draw neat graphs wherever required.
Use appropriate equations of motion when necessary.

Section A — Objective Questions

10 × 1 = 10 Marks

Q1. Which of the following is required to describe whether an object is at rest or in motion?

a) Mass
b) Reference point
c) Temperature
d) Volume

Q2. A runner completes one complete lap of a circular track and returns to the starting point. The displacement of the runner is:

a) Equal to the circumference
b) Half the circumference
c) Zero
d) Greater than the distance

Q3. Which quantity has both magnitude and direction?

a) Speed
b) Distance
c) Time
d) Velocity

Q4. A straight horizontal line on a distance-time graph indicates that the object is:

a) Moving with increasing speed
b) At rest
c) Moving with constant acceleration
d) Moving very fast

Q5. A steeper straight line on a distance-time graph represents:

a) Greater speed
b) Smaller distance
c) Zero speed
d) Greater time

Q6. If the velocity of an object decreases uniformly with time, its acceleration is:

a) Positive
b) Zero
c) Negative
d) Infinite

Q7. Which equation relates final velocity, initial velocity, acceleration and time?

a) s=vt
b) v=u+at
c) v=s/t
d) a=st

Q8. A body moving in a straight line with constant speed has:

a) Constant acceleration
b) Zero acceleration
c) Increasing acceleration
d) Negative velocity

Q9. A car travels 150 m in 10 seconds. Its speed is:

a) 10 m/s
b) 15 m/s
c) 20 m/s
d) 1500 m/s

Q10. The SI unit of acceleration is:

a) m
b) m/s
c) m/s²
d) km/h

Section B — Very Short Answer Questions

5 × 2 = 10 Marks

Q11. What is a reference point? Give one example showing why it is necessary for describing motion.

Q12. Can the magnitude of displacement ever be greater than the distance travelled? Give a reason.

Q13. What does the slope of a velocity-time graph represent?

Q14. What is meant by uniform velocity?

Q15. Write the three equations of motion used for uniformly accelerated motion.

Section C — Short Answer and Numerical Questions

4 × 3 = 12 Marks

Q16. A bus travels 240 km in 6 hours. Calculate its average speed in km/h and m/s.

Q17. Explain why the odometer of a vehicle measures distance rather than displacement.

Q18. A motorcycle moving at 8 m/s increases its velocity to 18 m/s in 5 seconds. Calculate its acceleration.

Q19. What information can be obtained from a distance-time graph? Explain how the graph differs for an object at rest and an object moving uniformly.

Section D — Application-Based and Numerical Questions

2 × 4 = 8 Marks

Q20. A student walks 600 m from home to a shop in 10 minutes and then walks another 400 m in the same direction to a friend’s house in 5 minutes.

Answer the following:

a) What is the total distance travelled?
b) What is the total time taken in seconds?
c) Calculate the average speed in m/s.
d) If the entire journey is along a straight line in the same direction, what is the magnitude of displacement?

Q21. A cyclist moving at 12 m/s applies the brakes and comes to rest in 4 seconds.

a) What is the initial velocity?
b) What is the final velocity?
c) Calculate the acceleration.
d) What does the negative sign of acceleration indicate?

Section E — Long Answer and Numerical Questions

2 × 5 = 10 Marks

Q22. Explain the difference between uniform and non-uniform motion. Also describe how the motion of an object can be represented using a distance-time graph. Include suitable examples.

Q23. A car is moving with an initial velocity of 5 m/s. It accelerates uniformly at 3 m/s² for 4 seconds.

Calculate:

a) Final velocity of the car.
b) Distance travelled during the 4 seconds.

Show all steps and write the equations used.

SOLUTIONS

Section A — Answers

Q1. b) Reference point

Q2. c) Zero

Q3. d) Velocity

Q4. b) At rest

Q5. a) Greater speed

Q6. c) Negative

Q7. b) v=u+at

Q8. b) Zero acceleration

Q9. b) 15 m/s

Q10. c) m/s²

Section B — Solutions

Q11. Reference Point

A reference point is a fixed point or object with respect to which the position and motion of another object are described.

For example, a passenger inside a moving bus is at rest relative to another passenger but is moving relative to a person standing on the roadside.

Thus, a reference point is necessary to determine whether an object is at rest or in motion.

Q12. Displacement and Distance

No. The magnitude of displacement cannot be greater than the distance travelled.

Distance represents the actual path travelled, whereas displacement is the shortest straight-line change from the initial position to the final position.

Therefore:Magnitude of displacement≤Distance

They are equal only in certain straight-line journeys without a change in direction.

Q13. Slope of a Velocity-Time Graph

The slope of a velocity-time graph represents acceleration.Acceleration=TimeChange in velocity

Therefore:a=tv−u

A positive slope indicates positive acceleration, while a negative slope indicates negative acceleration.

Q14. Uniform Velocity

An object has uniform velocity when it covers equal displacements in equal intervals of time in the same direction.

Since velocity includes both magnitude and direction, a change in direction means the velocity is not uniform even if the speed remains constant.

Q15. Equations of Motion

The three equations of motion for uniformly accelerated motion are:v=u+ats=ut+21at2v2−u2=2as

where:

u = initial velocity
v = final velocity
a = acceleration
t = time
s = displacement

Section C — Solutions

Q16. Average Speed of the Bus

Given:

Distance = 240 km

Time = 6 h

Average speed in km/h

Average Speed=6240=40 km/h

To convert km/h to m/s:40×185=1820011.11 m/s approximately

Answer:40 km/h≈11.11 m/s

Q17. Odometer and Distance

An odometer records the total length of the path travelled by a vehicle.

If a vehicle changes its direction or takes turns, the odometer continues to add the distance covered.

Therefore, it measures distance, not displacement.

Displacement depends only on the initial and final positions and includes direction.

Q18. Acceleration of the Motorcycle

Given:u=8 m/sv=18 m/st=5 s

Using:a=tv−ua=518−8a=510a=2 m/s2

Answer: The acceleration is 2 m/s².

Q19. Distance-Time Graph

A distance-time graph shows how the distance travelled by an object changes with time.

The slope of the graph gives the speed.

For an object at rest, the distance does not change with time, so the graph is a horizontal line.

For an object moving with uniform speed, equal distances are covered in equal intervals of time, so the distance-time graph is a straight line with a constant slope.

A steeper straight line represents a greater speed.

Section D — Solutions

Q20. Student’s Journey

The student travels:

First part = 600 m
Second part = 400 m

a) Total distance

600+400=1000 m1000 m

b) Total time

10 minutes + 5 minutes = 15 minutes

Convert into seconds:15×60=900 s900 s

c) Average speed

Average Speed=Total TimeTotal Distance=9001000=1.11 m/s approximately1.11 m/s

d) Displacement

The student travels in the same direction along a straight line.

Therefore, the magnitude of displacement is:600+400=1000 m1000 m

Q21. Braking Cyclist

Given:u=12 m/sv=0 m/st=4 s

a) Initial velocity

12 m/s

b) Final velocity

0 m/s

c) Acceleration

a=tv−ua=40−12a=−3 m/s2a=−3 m/s2

d) Meaning of negative acceleration

The negative sign indicates that the acceleration acts opposite to the chosen direction of motion. In this situation, the cyclist’s speed is decreasing, so the cyclist is decelerating.

Section E — Solutions

Q22. 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.

For example, if a car travels 20 m every second along a straight road, its motion is uniform.

For uniform motion, the speed remains constant.

Non-Uniform Motion

An object is in non-uniform motion when it covers unequal distances in equal intervals of time or when its direction changes.

For example, a car travelling through a busy city road may repeatedly speed up, slow down and stop.

Distance-Time Graph

A distance-time graph represents the relationship between distance and time.

A horizontal line represents an object at rest.
A straight sloping line represents uniform speed.
A curved line indicates changing speed.

The slope of a distance-time graph gives the speed of the object.

Thus, distance-time graphs help us understand how an object’s motion changes with time.

Q23. Motion of the Car