Class 9 Science MCQ Force and Laws of Motion

Question : A real gas at a very high pressure occupies
(a) Less volume then that of an ideal gas under identical condition
(b) More volume than that of an ideal gas under identical conditions
(c) Same volume than that of an ideal gas under identical conditions
(d) Cannot be predicted

Question : The masses of two bodies are in ratio 5 : 6 and their velocities are in ratio 1 : 2. Then their linear momentum will be in the ratio
(a) 5 : 6
(b) 1 : 2
(c) 12 : 5
(d) 5 : 12

Question : When a 12 N force acts on 3 kg mass for a second, the change in velocity is (in m/s)
(a) 36
(b) 4
(c) 2
(d) 18

Question : Temperature according to kinetic theory, is a measure of
(a) Average translational kinetic energy of gas molecules
(b) Intermolecular attraction
(c) Intermolecular distances
(d) Volume f gas

Question : A force is defined as a
(a) Fall
(b) Pull
(c) Push or Pull
(d) Push

Question : The acceleration of an object is
(a) inversely proportional to its mass
(b) directly proportional to the applied force
(c) resisted by inertia
(d) all of the above

Question : Change in momentum when a car weighing 700kg changes its speed from 100m/s to 200 m/s is:
(a) 14000 kg.m/s
(b) 10500000 kg.m/s
(c) 21000000 kg.m/s
(d) 70000 kg.m/s

Question :A body of mass 20 kg moves with an acceleration of 2ms–2. The rate of change of momentum in S.I. unit is –
(a) 40
(b) 10
(C) 4
(d) 1

Question :9.8 N is equal to-
(a) 1 kgf
(b) 1 kgwt
(C) A and B both
(d) Neither A nor B

Question :Newton used, ‘quantity of motion’ for-
(a) momentum
(b) force
(C) acceleration due to gravity
(d) none of these

Question : A cannon after firing recoils due to –
(a) conservation of energy
(b) backward thrust of gases produced
(C) Newton’s first law of motion
(d) Newton’s third law of motion

Question : Newton’s first law of motion is –
(A) qualitative
(b) quantitative
(C) both qualitative and quantitative
(d) neither qualitative nor quantitative

Question :When a bus starts suddenly the passengers standing on it, lean backwards in the bus. This is an example of –
(a) Newton’s first law
(b) Newton’s second law
(C) Newton’s third law
(d) none of Newton’s law

Question : The law which defines force is –
(a) Newton’s third law
(b) Newton’s first law
(C) Newton’s second law
(d) none of these

Question : An iron ball and aluminium ball has same mass:
(a) inertia of iron is greater than aluminium
(b) both the ball have same inertia
(C) inertia of iron is less than that of Aluminium
(d) none of these

Question : If A and B are two objects with masses 10 kgand 30 kg respectively then :
(a) A has more inertia than B
(b) B has more inertia than A
(C) A and B have the same inertia
(d) none of the two have inertia

Question : First law of motion defines-
(a) inertia
(b) force
(C) both inertia and force
(d) neither inertia nor force

Question :Momentum measures amount of ………… in a body-
(a) inertia
(b) motion
(C) velocity
(d) acceleration

Question : Force measures rate of change of ……….. a body
(a) mass
(b) inertia
(C) velocity
(d) momentum

Question : Mass measures amount of …………..in a body-
(a) inertia
(B) motion
(C) velocity
(d) acceleration

Question : C.G.S. unit of force is –
(a) m/s
(b) s/m
(C) dyne
(d) Newton

Question : If a moving ball A collides with another moving ball B, then
(a) momentum of A = momentum of B
(b) (momentum A + momentum of B) before collision = (momentum A + momentum of B) after collision
(C) neither A nor B
(d) A or B both are possible

Question : When a bullet is fired from a gun. The gun recoils to –
(a) conserve mass
(b) conserve momentum
(C) conserve K.E
(d) none of these

Question : Momentum has same unit as –
(a) impulse
(b) torque
(C) moment of force
(d) couple

Question : When force of 1 N acts on mass of 1 kg, whichis able to move freely, the object moves with a/an –
(a) speed of 1 ms–1
(b) speed of 1 kms–1
(C) acceleration of 10 ms–2
(d) acceleration of 1 ms–2

Question : The net force acting on a body of mass of 1 kg moving with a uniform velocity of 5 ms–1 is –
(a) 5 N
(b) 0.2 N
(C) 0 N
(d) None of these

Question : A body of mass M strikes against wall with a velocity v and rebounds with the same velocity. Its change in momentum is –
(a) zero
(b) Mv
(C) –Mv
(d) –2 Mv

Question :Gram weight is a unit of-
(a) mass
(b) weight
(C) A and B both
(d) neither A nor B

Question :A body of mass 5 kg undergoes a change in speed from 20 m/s to 0.20 m/s. The momentum-
(a) increases by 99 kgm/s
(b) decreases by 99 kgm/s
(C) increases by 101 kgm/s
(d) decreases by 101 kgm/s

Question :Choose correct relation :
(a) a = F/m
(b)aF = m
(C) m = F × a
(d) none of these

Question :Inertia of rest is the property by virtue of which
the body is unable to change by itself:
(A) the state of rest only
(b) the state of uniform linear motion
(C) the direction of motion only
(d) the steady state of rest

Question :A bullet in motion hits and gets embedded in a solid resting on a frictionless table. What is conserved ?
(a) Momentum and K.E.
(b) Momentum alone
(C) K.E. alone
(d) None of these

Question :Choose correct statement-
(a) Action and reaction forces act on same object.
(b) Action and reaction forces act on different objects.
(C) A and B both are possible.
(d) Neither A nor B is correct.

Question : The combined effect of mass and velocity is taken into account by a physical quantity called
(a) torque
(b) moment of force
(C) momentum
(d) all of them

Question : How many dynes are equal to 1 N ?
(a) 106
(b) 104
(C) 105
(d) 103

Question :A bullet of mass 0.01 kg is fired from a gun weighing 5.0 kg. If the initial speed of the bullet is 250 m/s, calculate the speed with which the gun recoils-
(a) – 0.50 m/s
(b) – 0.25 m/s
(C) + 0.05 m/s
(d) + 0.25 m/s

Question :A man is standing on a boat in still water. If he walks towards the shore the boat will –
(a) move away from the shore
(b) remain stationary
(C) move towards the shore
(d) sink