Question

A body, when acted upon by a force of 20 kgf, gets displaced by 1 m. Calculate the work done by the force, when the displacement is

1. in the direction of force,
2. at an angle of 60° with the force, and
3. normal to the force. (g = 10 N kg^-1)

Answer 1

F = 20 kgf = 20 × 10 N = 200 N

Displacement S = 1 m

Work done

1. When displacement is in the direction of force
   W = F × S
   W = 200 × 1 = 200 J
2. When displacement is at an angle of 60°
   W = F.S cos 60°
   = 200 × 1 × `1/2`
   = 100 J
3. When displacement is normal to the direction of force
   W = F.S cos 90°
   = 200 × 1 × 0
   = 0 (Zero)