Question
The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative:
(d) work done by an applied force on a body moving on a rough horizontal plane with uniform velocity
Solution
Positive quantity.
In this case, the body is moving on a rough horizontal plane. Frictional force opposes the motion of the body. Therefore, in order to maintain a uniform velocity, a uniform force must be applied to the body. Since the applied force acts in the direction of motion of the body, the work done is positive.
In this case, the body is moving on a rough horizontal plane. Frictional force opposes the motion of the body. Therefore, in order to maintain a uniform velocity, a uniform force must be applied to the body. Since the applied force acts in the direction of motion of the body, the work done is positive.
