Science Question Bank SA - 1 - CBSE (CCE)
FORCE AND LAWS
OF MOTION
9
Exercise 9.1
Topics :
Balanced and unbalanced forces.
Laws of motion.
Conservation of momentum.
1 MARK
1.
If mass of a body is doubled, what happens to its acceleration under a given force?
(2014)
F
Ans. a = m
F
If m = 2m, a = 2m
The acceleration is reduced to its half.
2.
Why are small kids advised to play cricket with soft tennis ball rather than leather ball?
(2014)
Ans. As soft tennis ball has less mass, the impact of force produced by it will less and the
small kids will not get hurt.
3.
Name the principle on which a rocket works.
(2014)
Ans. Newton’s Third Law of Motion.
4.
Find the force required to accelerate a 2kg mass by 5 ms-2.
(2014)
Ans. F = ma
5.
= 2 x 5 = 10N
If a balloon filled with air and its mouth untied, the air is released from its mouth in the
downward direction and balloon moves upwards. Identify action and reaction in this
case. (2014)
Ans.Action → Release of air in the downward direction.
Reaction → Upward movement balloon.
6.
A body of mass 30 kg has a momentum of 150 kgms-1. Find its velocity.
(2014)
Ans. p = mv
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TEACHERS FORUM
Science Question
Bank
1 - CBSE (CCE)
Force and
LawsSA
of-Motion
7. p
150
v = m = 30 = 5 m/s
A force is applied on a metal block lying on floor in one direction. Still the block does
not move. Name the force which is balancing it.
(2014)
Ans. Force of friction between metal surface and floor.
8.
State two effects, a force can produce in a non rigid body fixed at a position. (2011)
Ans.Shape and size.
9.
(2011, 2013)
In a tug of war, the rope does not move in any direction. Why ?
Ans. Because the forces applied by the two teams are equal and in opposite directions.
10. When the driver of a bus applies sudden brakes, the passengers fall forward. Why ?
(2014)
Ans. It is due to inertia of motion
11. Name the two physical quantities that are a measure of momentum.
(2012)
Ans. Mass and velocity
12.Why do passengers in a bus tend to fall backward when it starts suddenly?
(2013)
Ans.When the bus starts suddenly it gains the speed but our body tends to remain in its
state of rest due to inertia of rest and we fall backward.
13.While riding on the bicycle if we stop pedaling why does the bicycle begin to slow
down ? (2014)
Ans.Here the frictional force is acting opposite to the direction of motion.
14. An unbalanced force is acting on an object. List the possible effects that will be
caused in the motion of object.
(2012, 2013)
Ans.Either change the speed or change the direction of motion.
15. Name the factor on which the inertia of a body depends ?
(2011)
Ans.Mass.
16.“Action and reaction are equal and opposite but even then they do not cancel
each other”. Give reason.
(2012)
Ans.Because they act on two different bodies.
17. Which one has greater inertia : a stone of mass 1kg or a stone of mass 5 kg ? (2013)
Ans. Stone of mass 5 kg
18. Name the force which is responsible for change in position or state of an object. (2014)
Ans. Unbalanced forces
19. State the meaning of balanced forces.
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(2011, 2013)
TEACHERS FORUM