No work is done by a force on an object if
a) the force is always perpendicular to its velocity
b) the force is always perpendicular to its acceleration
.c) the object is stationary but the point of application of the force moves on the object
d) the object moves in such a way that the point of application of the force remains fixed.

Options

A. b, c & d are correct
B. a, b & d are correct
C. a, c & d are correct
D. all are correct

Answer

C