RBSE Class 9 Science Solutions Chapter 8 Motion

August 3, 2022November 30, 2025

RBSE Class 9 Science Chapter 8 Motion InText Questions and Answers

Page No. 100

Question 1.
An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.
Answer:
Yes, an object can have zero displacement provided that final position of the object coincides with its initial position.
For example : If a person moves from home to store and stands on place from where he started then here displacement will be zero.

Question 3.
Which of the following is true for displacement?
(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.
Answer:
None of the statement is true for displacement. First statement is false because displacement can be zero. Second statement is false as displacement is less than or equal to the distance travelled by the object.

Page No. 102

Question 1.
Distinguish between speed and Velocity.
Answer:

Speed	Velocity
Speed is the distance travelled by an object in a given interval of time.	Velocity is the displacement of an object in a given interval of time.

Scalar quantity, i.e. it has only magnitude.	Vector quantity, i.e. it has both magnitude as well as direction.

Question 2.
Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?
Answer:
The magnitude of average velocity of an object is equal to its average speed when an object is moving in a straight line in a given direction only.

Question 3.
What does the odometer of an automobile measure?
Answer:
The odometer of an automobile measures the distance covered by an automobile in given time.

Question 4.
What does the path of an object look like when it is in uniform motion?
Answer:
When an object having uniform motion, it moves along a straight line path.

Question 5.
During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3 × 10⁸ ms^-1.
Answer:
Speed = 3 × 10⁸ ms^-1
Time = 5 min = 5 × 60 = 300 seconds
Distance = Speed × Time
Distance = 3 × 10⁸ ms^-1 × 300 seconds = 9 × 10¹⁰ m

Page No. 103

Question 1.
When will you say a body is in (i) uniform acceleration? (ii) non-uniform acceleration?
Answer:

A body is said to be in uniform acceleration if it travels in a straight line and its velocity increases or decreases by equal amounts in equal intervals of time.
A body is said to be in non-uniform acceleration if the rate of change of its velocity is not constant.

Question 4.
What is the quantity which is measured by the area occupied below the velocity-time graph?
Answer:
Area occupied below the velocity-time graph of an object gives the magnitude of displacement or the distance covered during the given time interval.

Page No. 109-110

Question 1.
A bus starting from rest moves with a uniform acceleration of 0.1 m s^-2 for 2 minutes. Find (a) the speed acquired, (b) the distance travelled.
Answer:
Initial speed of the bus, u = 0
Acceleration, a = 0.1 m/s²
Time taken, t = 2 minutes = 120 s
(a) ν = u + at
ν = 0 + 0.1 × 120
ν = 12 ms^-1
Speed acquired by the bus is 12 m/s.

(b) According to the third equation of motion :
ν² = u² = 2 as
Where, s is the distance covered by the bus
(12)² – (0)² = 2(0.1) s
s = 720 m
Distance travelled by the bus is 720 m.

RBSE Class 9 Science Chapter 8 Motion Textbook Questions and Answers

Question 1.
An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?
Answer:

Question 6.
Fig. shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions :

Distance-time graph of three objects A, B and C
(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C?
Answer:
(a)
RBSE Solutions for Class 9 Science Chapter 8 Motion 20
Therefore, speed = slope of the graph
Since slope of object B is greater than objects A and C, it is travelling the fastest.
(b) All three objects A, B and C never meet at a single point. Thus, they were never at the same point on road.
(c)