posted by Anonymous .
A car with a mass of 1500kg starts from rest and accelerates to a speed of 18m/s in 12s. Assume that the force of resistance remains constant at 400N during this time. What is the average power developed by the car's engine?
a = (Vf - Vo) / t,
a = (18 - 0) / 12 = 1.5 m/s^2.
Fn = Fap - 400 = 1500 * 1.5,
Fap - 400 = 2250,
Fap = 2650 N. = Force applied.
Vave = (0+18) / 2 = 9 m/s. = Average velocity.
P = Fap * Vave = 2650 * 9 = 23,850 Joules/s = 23,850 Watts.