Question

Work is done when...
a. the displacement is not zero
b. the displacement is zero
c. the force is zero
d. the force and displacement are perpendicular

Answer 1

jk it's A. I figured it out!

Answer 2

work is done when there is a non-zero component of force in the direction of displacement( which again should be non-zero).
Which looks obvious from it's formula:\[dW = F \cos \theta *dx\]