# Laws Of Motion

## The combined effect of mass and velocity is taken into account by a physical quantity called:

A
Moment of momentum
B
Moment of force
C
Momentum
D
None of these
Easy
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## When an athlete takes part in a long jump he runs for a while and then jumps. This is because:

A
inertia of motion helps him to take a longer jump.
B
running for a time makes him alert.
C
it helps him to focus on the point of jump.
D
he can apply more force for the jump after running.
Easy
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## When a moving body is suddenly stopped, then:

A
Frictional force increases.
B
Friction force remains same as it was while the car was moving.
C
Friction force reduces but has a non zero value.
D
Frictional force reduces to zero as it is a self adjusting force.
Easy
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## A stone tied to a string is rotated in a vertical circle. The minimum speed with which the stone has to be rotated in order to complete the circle :

A
decreases with increasing the mass of the stone
B
is independent of the mass of the stone
C
decreases with increasing the length of the string
D
is independent of the length of the string
Easy
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## Impulse is equal to

A
momentum
B
change in momentum
C
rate of change of momentum
D
rate of change of force
Easy
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Assertion

Reason

## It is due to inertia of rest.

A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C
Assertion is correct but Reason is incorrect
D
Assertion is incorrect but Reason is correct
Easy
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## In which of the following cases the net force is not equal to zero?

A
A kite skillfully held stationary in the sky.
B
A ball falling freely from a height.
C
A helicopter hovering above the ground.
D
A cork floating on the surface of water.
Easy
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