A load of mass 100 kg is pulled by a horse on a horizontal ground with a constant horizontal force 1000 N. The frictional force between the load and the horizontal ground is 200 N. What is the velocity of the load and the work done by the horse after the load is pulled through a distance of 4.0 m?

Answer 1

M = 100kg
F = 1800N
S = 4.0m

W = F S
W = (1800N)(4.0m) = 7200Nm
W = 7.2 kJ

A = F / M
V = V0 + A T
S = S0 + V0 T + ½ A T^2

Assume initial velocity and displacement are 0.

S = ½ F T^2 / m
T = √(2 M S / F)
V = F √(2 M S / F) / M
V = √(2 F S / M)
V = √(2 1800N 4.0m / 100kg)
V = 12 m/s