Online Test of Chapter 9 Force and Laws of Motion 1 Science| Class 9th

1. An unbalanced force is necessary for an object to be
(i) at reset
(ii) in motion with a constant velocity
(iii) accelerated
(iv) all of the preceding

2. Bags at the top of a school van are tied using a string to avoid the effect of
(i) inertia
(ii) momentum
(iii) force
(iv) acceleration

3. Inertia
(i) sets objects in motion
(ii) causes changes in motion
(iii) is the result of a net force
(iv) is directly proportional to the mass of an object

4. A plate, a ball and a child all have the same mass. The one having more inertia is the
(i) plate
(ii) ball
(iii) child
(iv) All have equal inertia

5. A passenger in a moving train tosses a coin which falls behind him. It means that the motion of the train is
(i) accelerated
(ii) uniform
(iii) retarded
(iv) along circular tracks

6. Two equal masses m each moving in the opposite direction with the same speed v collide and stick to each other. The velocity of the combined mass is
(i) v
(ii) 2v
(iii) v/2
(iv) zero

7. The rate of change of momentum with respect to time is measured in
(i) kg ms^-2
(ii) kg ms^-1
(iii) kg m
(iv) kg

8. The incorrect option regarding action-reaction pair is
(i) they are equal and opposite
(ii) they act on two different bodies
(iii) they act only between bodies in contact
(iv) their sum on the body is zero

9. A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goalkeeper to
(i) exert larger force on the ball
(ii) reduce the force exerted by the ball on hands
(iii) increase the rate of change of momentum
(iv) decrease the rate of change of momentum

10. If force, change in momentum and time are given by F, p and t respectively, then they are related b
(i) F=pt
(ii) F = p/t
(iii) Ft² = p
(iv) p = F²t