No work is done by a force on an object if

Options

A. the object is stationary but the point of aplication or the force moves on the object
B. the object moves in such a way that the point of application of the force remains fixed
C. the force is always perpendicular to its velocity
D. the force is always perpendicular to its acceleration.

Answer

A, B, D

Explanation

`W=Fcos theta=0`, when either `s=0` or `theta=90^(@) i.e.` when object is stationary but the point of application fo the force moves on the object or object moves in such a way that point of application of force remains fixed, or force is at `90^(@)` to the acceleration. Choice `(a), (b), (d)` are correct.