A motorcycle has a mass of 1000 kg. The motorcycle is slowed from 50 km/hr to a stop in 5s. What is the net force causing the deceleration?
Vo = 50km/h = 50,000m/3600s = 13.89 m/s.
a = (V-Vo)/t = (0-13.89)/5 = -2.78 m/s^2
F = m*a = 1000 * (-2.78) = -2780 N.
The negative sign means the force is
against the motion.