Question

Work done is zero if an object moves with constant velocity? Right?

Answer 1

Hint: Here in the given question, it is given that velocity is constant when we are calculating the work done by an object. When we apply some force on any object then the object tends to do some work in the form of displacement.

Complete answer:
When we are talking about the work done in physics, we are also discussing the force applied on the body also. When we apply some force on any object then the object tends to do some work in the form of displacement.
Work done is the dot product of the force applied on the object and displacement of the object.
Work done$ = F.d\cos \theta $
Here, $F$ is the force applied on the object and $d$ is the displacement of the object due to that force.
Here, in the formula of work done force is considered therefore we can say that for work done to be non-zero acceleration should be non-zero. That’s why work done is zero if the acceleration is zero.
Now consider if the velocity of the object is constant that gives us the zero acceleration therefore the force is equal to zero, that implies that work done is zero.

Note: For work done to be zero there can be some possibilities that are: force is equal to zero, displacement is equal to zero or the angle between the displacement and the force should be ${90^{\text{o}}}$ . For example, if a person pushes a wall with $20{\text{N}}$ force but the displacement of the wall is zero, therefore this is the zero-work condition. When you hold a bag and don’t move that means you are exerting a force but the displacement is zero therefore that is an example of zero work condition.