In which of the following, the work done by the mentioned force is negative?
The work done by the tension of the cable while the lift is ascending.
The work done by the gravitational force when a body slides down an inclined place.
The work done by the applied force in maintaining uniform motion of a block on a rough horizontal surface.
The work done by the gravitational force when a body is thrown up.
A
The work done by the tension of the cable while the lift is ascending.
B
The work done by the gravitational force when a body slides down an inclined place.
C
The work done by the applied force in maintaining uniform motion of a block on a rough horizontal surface.
D
The work done by the gravitational force when a body is thrown up.
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Solution
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When a body is thrown up the gravitational force acts opposite to the displacement of the body. The work done being a dot product of force and displacement vectors, becomes negative as cosine of 180 degrees is -1.
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