Please help and explain this problem. Preferably step by step. Thanks!!

A 3000kg train accelerates from rest to a velocity of 30m/s in 10s. The engine's power during this acceleration is ______.

Question

Please help and explain this problem. Preferably step by step. Thanks!!

A 3000kg train accelerates from rest to a velocity of 30m/s in 10s. The engine's power during this acceleration is ______.

anonymous · Answer

There no mention of friction. So, we can assume that the entire power generated by the engine is converted into its Kinetic Energy.

Initial KE = 0J (zero initial velocity)
Final  KE = 1/2 * m * v^2
    = 1/2 * 3000 * 30^2 
    = 1.35 * 10^6 J

Therefore average power = (Final KE - Initial KE)/t
    = 1.35*10^6 / 10
    = 135 kW