Question

The wheels of a midsize car exert a force of 2150 N on the road to accelerate the car in the forward direction. If the force of friction including air resistance is 225 N and the acceleration of the car is 1.50 m/s2, what is the mass (in kg) of the car plus its occupants?

Answer 1

Apply Newton's second law to the car's motion:

F = ma

F = net force, m = mass, a = acceleration

The net force F is the difference of the force the car exerts on the road and the frictional/air drag forces:

F = 2150N - 225N

F = 2128N

Back to F = ma

Given values:

F = 2128N, a = 1.50m/s²

Plug in and solve for m:

2128 = m(1.50)

m = 1420kg