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Question
The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:
Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity.
Solution
The work done by an applied force on a body moving on a rough horizontal plane with uniform velocity is positive. This occurs because the applied force and the displacement occur in the same direction. Hence, θ = 0°
`W = Fdcosθ = Fdcos0° =Fd` (positive)
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