posted by S5 .
A motor car of mass 2000kg accelerates from rest at 3 ms-2 for 4s on a straight road. find the average useful output power of the engine of the car.
Find the change in kinetic energy in Joules and divide by 4 seconds to get average power.
v = a t = 3(4) = 12 m/s final
Ke = (1/2)(2000)(144) Joules
power = Ke/4 Watts