Saturday, 25 October 2014

Chapter 9 Force And Laws Of Motion | Physics | MCQs | Class 9th | - Multiple Choice Questions

Question 1. An object of mass 6 kg is sliding on  horizontal surface, with a uniform velocity of 8 m/ s . Assuming force of friction offered by the surface to be zero,  The force required to maintain the motion of object  with the same uniform velocity is

(a) 0 Newton
(b) 2 Newtons
(c) 8 Newtons
(d) 32 Newtons

Answer. (a) 0 Newton



Question 2. There will be a change in the speed or in the direction of motion of a body when it is acted upon by

(a) Zero Force
(b) Balanced Force
(c) An Unbalanced force
(d) Uniform force

Answer. c) An Unbalanced force

Question 3. Force required in accelerating a 3 kg mass at 5 m/s2 and a 4 kg mass at 4 m/s2, will be

(a) Zero in both the cases
(b) Same in both the cases
(c) greater for 3 kg mass at 5 m/s2
(d) greater for 4 kg mass at 4 m/s2
Answer. (d) greater for 4 kg mass at 4 m/s2

Question 4. Which of the Expression to find the Force is correct ?

(a) F= m/a
(b) F= ma
(c) F= a/m
(d) F= ma/m

Answer. F= ma

Question 5. Inertia of a body is quantitative measure of its.

(a) velocity
(b) acceleration
(c) Mass
(d) Force

Answer. (c) Mass

Question 6. Rocket works on the principle of conservation of

(a) velocity
(b) Mass
(c) Linear Momentum
(d) Energy

Answer. (c) Linear Momentum

Question 7. In the following example, try to identify the number of times the velocity of ball changes:
“A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team.”


(a) Three times
(b) Four times
(c) Five times
(d) Six times

Answer. (a) Three times

Question 8. A bullet of mass 40gm is fired from a gun of mass 8kg with a velocity of 800 m/s, calculate the recoil velocity of gun

(a) 1m/s
(b) -1m/s
(c) 2m/s
(d) -4m/s

Answer. (d) -4m/s

Question 9. A passenger in a moving train tosses a coin. The coin will fall back

(a) Behind him
(b) In front of him
(c) On his hands
(d) On the side of the train

Answer. (c) On his hands

Question 10. A hammer of mass 300 g, moving at 40m/s, strikes a nail. The nail stops the hammer in a very short time of 0.02 s. The force of the nail on the hammer is

(a) 600N
(b) 1200N
(c) 2000N
(d) 2500N

Answer. (a) 600N

Chapter 9 Force And Laws Of Motion | Physics | MCQs | CBSE Class IX (9th) Science | - Multiple Choice Questions

Question 11. The action and reaction forces referred to in the third law

(a) May act on different objects
(b) Must act on different objects
(c) Must act on the same object
(d) Need not be equal in magnitude but act in the same direction

Answer. (b) Must act on different objects

Question 12. An object will continue to accelerate until the

(a) The velocity changes direction
(b) Resultant force on it is increased continuously
(c) Resultant force begins to decrease
(d) Resultant force on it is zero

Answer. (d) Resultant force on it is zero

Question 13. Type of inertia that tends to resist the change in case of an “Athlete often jumps before taking a long jump “

(a) Inertia of direction
(b) Inertia of motion
(c) Uniformly accelerated motion
(d) Inertia of rest

Answer. (b) Inertia of motion

Question 14. Qualitative definition of Force is given by

(a) Newton’s law of gravitation (b) Newton’s first law of motion
(c) Newton’s Second law of motion
(d) Newton’s third law of motion


Answer. (b) Newton’s first law of motion

Question 15. The object shown below moves with constant velocity. Two forces are acting on the object.

Considering negligible friction , the resultant force will be


(a) 3 N towards left
(b) 5 N towards right
(c) 10 N towards left
(d) 19 N towards left

Answer. (b) 5 N towards right
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