In a certine situation , `vec F` and `vec S` are not equal to zero but the work done is zero from this , we conclude that

In a certain situation , vec F and vec S are not equal to zero but the work done is zero from this , we conclude that

The work done by a force is defined by W= vec F cdot vec S cdot It is found that the work done is zero, even if vec F and vec s are not equal to zero. From this we conclude that

If vec a and vec b are two non -zero vectors, then (vec a + vec b) .(vec a - vec b) is equal to