Q. 9

# One end of a light spring of spring constant k is fixed to a wall and the other end is tied to a block placed or a smooth horizontal surface. In a displacement, the work done by the spring is the possible cases are

A. the spring was initially compressed by a distance x and was finally in its natural length

B. it was initially stretched by a distance x and finally was in its natural length

C. it was initially in its natural length and finally in a compressed position

D. it was initially in its natural length and finally in a stretched position.

Answer :

Work done is +ve on when the force applied, and displacement are in the same direction. But here in case of options C and D the spring does not exert a force that is in the direction of displacement but in the opposite, so the work done will be negative. In case of option A and D the work done will be positive.

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