A certain vehicle can accelerate from rest to a speed of 25m/s in a time of 8s.What average power is needed to cause this acceleration?Neglect frictional losses
KE gained=1/2 m vf^2
power used=KEgained/time=1/2 m vf^2/8sec
= 1/2 mass*25^2/8 watts
So you need to know mass of the car: it takes much more power to accelerate a heavy car.