Question

A force f is applied on an object and it is displaced by distance d give expression for work done when angle between force and displacement are
a)0°
b)180°

Answer 1

Given that

Force = f

displacement = d

case 1

when angle = 0°

expression

W = f × d × cos0°

W = f × d ×1

W = fd

case 2
when angle = 180°

W = f × d × cos180°

W = f × d × (-1) [because cos180° = -1]

W = - fd