Given; m = 50 kg;

μ_{8} = 0.2, d = 100 m

The limiting friction force

Work done W = Fd cosθ

The angle between frictional force and displacement

θ = 180°

cosθ = cos 180° = -1

And F = f_{s} = 100 N

∴ The work done by force of friction

W = Fd cosθ = 100 × 100 x(-1)

or W=-10^{4} j

Angle between force applied F and displacement,

0 = 0°

∴ cos0 = 1

∴ W = 100 × 100 × 1 = 10^{4} J

or W = 10^{4} J