The amount of work done is measured in terms of joule denoted as J. It is also the same as newton-meter (N-m).
Positive Work: The work done is positive, if the object moves in the same direction as the force applied.
For example, when you move a chair the work done is in the forward direction and so the chair moves forward.
If the displacement of the object is in the opposite direction of the applied force, then the work done is negative.
All objects that are thrown up in the air are moving against the gravitational force. Thus the work done is negative.
Zero Work: When the force applied & displacement of the object are perpendicular to each other, the work done is ‘zero’.
If the force is applied to an object but if the object doesn’t move, then the work done on it is zero. Pushing a mountain is also an example of zero work done.
Hope now you can clearly define positive work and zero work.