# Work Energy And Power

## The amount of work done in stretching a spring from a stretched length of 10 cm to a stretched length of 20 cm is-

A
Equal to the work done in stretching it from 20 cm to 30 cm
B
Less than the work done in stretching it from 20 cm to 30 cm.
C
More than the work done in stretching it from 20 cm to 30 cm.
D
Equal to the work done in stretching it from 0 to 10 cm.
Easy
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## A ball tied to a string is swung in a vertical circle. Which of the following remains constant?

A
Tension in the string.
B
Speed of the ball.
C
Centripetal force.
D
Earth's pull on the ball.
Easy
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## A lighter body moving with a velocity collides with a heavier body at rest. Then :

A
the lighter body rebounces with twice the velocity of bigger body
B
the lighter body retraces its path with the same velocity in magnitude
C
the heavier body does not move practically
D
both (2) and (3)
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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