Chapter 8.  Motion 

Class 9 Science Examplar Chapter 8 : MOTION Choose the correct answers : 

Q1. An object travels 16 m in 4 s and then another 16 m in 2 s , then the average speed of the object is :

(A) 3.35 m/s

(B) 5.33 m/s

(C) 5.22 m/s

(D) 3.52 m/s

Ans : (B) 5.33 m/s

[Average speed  m/s ]

Q2. The  of an object is the change in velocity per unit time .

(A) Speed

(B) Velocity

(C) Distance

(D) Acceleration

AnS : (D) Acceleration

Q3. A bus starting from rest moves with a uniform acceleration of  for 2 minutes , then the speed acquired is :

(A) 12 m/s

(B) 10 m/s

(C) 15 m/s

(D) 16 m/s

Ans : (A) 12 m/s

[ Here,

   

We have ,

  ]

Q4. The area under the distance-time graph gives :

(A) Non-uniform speed

(B) Velocity and Speed

(C) Uniform speed

(D)  (A) and (C)

Ans : (D)  (A) and (C)

Q5. The odometer of a car measures :

(A) Distance

(B) Speed

(C) Acceleration

(D) Velocity

Ans : (A) Distance

Q6. The S.I. unit of an acceleration is :

(A)  m/s      

(B)  

(C)  

(D) ms

Ans : (C)  

Q7. If the athlete takes  seconds to go once around the circular path of radius,the velocity  is given by :

(A)   

(B)  

(C)  

(D)   

Ans : (C)   .

Q8. A train starting from a railway station and moving with uniform acceleration attains a speed  40 km/h , in 10 minutes , then its acceleration is :

(A)   

(B)  

(C)  

(D)   

Ans : (C)  

[Here,

 m/s

   

We have ,

  ]

Q9. A particles is moving in a circular path of radius. The displacement after half a circle would be :

(A) Zero

(B) 

(C) 

(D) 

Ans : (C)    .

Q10. A body is thrown vertically upward with velocity, the greatest height   to which it will rise is ,

(A)   

(B) 

(C) 

(D)   

Ans :  (B)    .

Q11. The numerical ratio of displacement to distance for a moving object is :

(A) always less than 1

(B) always equal than 1

 (C) always more than 1

(D) equal or less than 1

Ans : (D) equal or less than 1 .

Q12. If the displacement of an object is proportional to square of time,then the object moves with

(A) uniform velocity

(B) uniform acceleration

(C) increasing acceleration

(D) decreasing acceleration

Ans : (B) uniform acceleration  .

Q13. From the given  graph (fig. 8.1) , it can be inferred that the object is :

(A) in uniform motion

(B) at rest

(C) in non-uniform motion

(D) moving with uniform acceleration 

Ans : (A) in uniform motion .

Q14.  Suppose a boy is enjoying a ride on a merry-go-round which is moving with a constant speed of 10m/s . It implies that the boy is :

(A) at rest

(B) moving with no acceleration

(C) in acceleration motion

(D) moving with uniform velocity

Ans : (C) in acceleration motion . 

Q15. Area under a  graph represents a physical quantity which has the unit :

(A)   

(B) m

(C) 

(D) m/s

Ans : (B) m .

Q16. Four cars A , B , C and D are moving on a leveled road . Their distance versus time graphs are shown in fig . 8.2 . Choose the correct statement :

(A) Car A is faster than car D

(B) Car B is the slowest

(C) Car D is faster than car C .

(D) Car C is the slowest . 

Ans : (B) Car B is the slowest  .

Q17. Which of the following figures (Fig. 8.3) represents uniform motion of a moving object correctly ?

Ans : (a)

Q18.  Slope of a velocity – time graph gives

(A) the distance

(B) the displacement

(C) the acceleration

(D) the speed

Ans : (C) the acceleration  .

Q19. In which of the following case of motions , the distance moved and the magnitude of displacement are equal ?

(A) If the car is moving on straight road

(B) If the car is moving in circular path

(C) The pendulum is moving to and fro

(D) The earth is revolving around the sun

Ans : (A) If the car is moving on straight road .

Q20. If an object’s speed and direction of motion changes .

(A) its speed change

(B) its uniform velocity

(C) its non-uniform velocity

(D) both (B) and (C)

Ans : (C) its non-uniform velocity .

Q21. The velocity-time graph represents :

(A) Body is stationary

(B) Body is in uniform motion

(C) Distance travelled by the body

(D)  None of these

Ans : (B) Body is in uniform motion .

Class 9 Science Examplar Chapter 8 : MOTION Fill in the blanks :

Q22. The shortest distance measured from the initial to the final position of an object is known as the  .

Ans : displacement .

Q23. The object covers equal distances in equal intervals of time, it is said to be in  .

Ans : uniform motion .

Q24. When an object moves in a circular path with uniform speed, its motion is called  motion .

Ans : uniform circular .

Q25. The   of an object is the change in velocity per unit time .

Ans : acceleration .

Q26. The  of an object is the distance covered per unit time .

Ans : speed .

Q27. The  is the displacement per unit time .

Ans : velocity .