A bicycle takes 8 seconds to accelerate at a constant rate from rest to a speed of 4 m/s. If the mass of the bicycle and rider together is 85 kg, what is the net force acting on the bicycle?

Force, F = ma

F = m (v-u) / t

Where F is force in Newtons, m = mass in kg = 85kg, v = final velocity, = 4m/s, u = initial velocity = 0 m/s, t = time = 8 seconds.

F = 85 * (4 - 0) / 8 = 42.5

Force = 42.5 N