# Online Test of Chapter 9 Force and Laws of Motion 2 Science| Class 9th

1. According to Newton’s third law of motion, action and reaction
(i) always act on the same body
(ii) always act on different bodies in opposite direction
(iii) have same magnitudes and direction
(iv) act on either body at normal to each other

2. The minimum number of unequal forces that can make zero resultant is
(i) two
(ii) three
(iii) four
(iv) ten

3. An object of mass 2 kg is sliding with a constant velocity of 4 ms-1 on a frictional horizontal table. The force required to keep the object moving with same velocity is
(i) 2 N
(ii) 8 N
(iii) 32 N
(iv) 0 N

4. A mass M breaks into two pieces in the ratio 1 : 3 while at rest. If the heavier has a speed of v, the speed of the lighter is
(i) v
(ii) 2v
(iii) 3v
(iv) 4v

5. An object of mass of 2 kg is sliding with a velocity of 4 ms-1 on a frictional horizontal surface. The retarding force necessary to stop the object in 1 second is
(i) 2 N
(ii) 4 N
(iii) 8 N
(iv) 0 N

6. The two states of motion treated alike by the Newton’s first law, among A, B, C and D are
A : Rest
B : Uniform motion
C : Uniformly accelerated
D : Non-uniformly accelerated
(i) A, D
(ii) A, B
(iii) A, C
(iv) B, C

7. Passengers standing in a bus are thrown outwards when the bus takes a turn suddenly. This happens because of
(i) outward pull on them
(ii) inertia
(iii) change in momentum
(iv) change in acceleration

8. When a 12 N force acts on 3 kg mass for a second, the change in velocity is (in m/s)
(i) 36
(ii) 4
(iii) 2
(iv) 18

9. A force of ‘P* N acts on a particle so as to accelerate it from rest to a velocity ‘v’ m/s. The force ‘P’ is then replaced by ‘Q’ N which decelerates it to rest.
(i) P may be equal to Q
(ii) P must be equal to Q
(iii) P must be unequal to Q
(iv) none of these

10. Which of the following does not happen? As an automobile accelerates suddenly,
(i) a toy monkey hung from the roof moves back
(ii) a standing person gets pushed back
(iii) a bag at the roof gets displaced backward
(iv) a person in the seat is pushed in front

## Class 9 Force and Laws Of Motion MCQ - 2

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