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A man is standing on a plank which is pl...

A man is standing on a plank which is placed on smooth horizontal surface. There is sufficient friction between feet of man and plank. Now man starts running over plank, correct statement is/are

A

Work done by friction on man with respect to ground is negative.

B

Work done by friction on man with respect to ground is positive

C

Work done by friction on plank with respect to ground

D

Work done by friction on man with respect to plank is zero.

Text Solution

Verified by Experts

The correct Answer is:
A, C, D

At contact point of man and plank, the relative motion is zero. As plank moves backward, man's foot also moves backwards, but friction on man acts forward. Hence workdone by friction on man is negative. But with respect to plank, foot will be at rest, hence no work done by friction on man w.r.t plank.
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