Question

identify this forces . which one of the two does a) positive work ? b) negative work ? justify your answer.

Answer 1

Positive work because it is a positive

Answer 2

 If a force displaces the object in its direction, then the work done is positive
So, W=Fd
The example of this kind of work done is motion of ball falling towards ground where displacement of ball is in the direction of force of gravity.

If the force and the displacement are in opposite directions, then the work is said to be negative. For example if a ball is thrown in upwards direction, its displacement would be in upwards direction but the force due to earth’s gravity is in the downward direction.