Question

A car accelerates from rest to 100 m/s in 10 seconds. If the mass of the car is 50 kg then power developed by the engine is___KW.

Answer 1

The change in kinetic energy of the car would be equal to the work done by the engine. Since power is work done per unit time, so change in kinetic energy of the car and the time which is taken for the change gives us the power developed by the engine i.e.
Work done $=\frac{1}{2}\times m\times v^2=\frac{1}{2}\times 50\times {100}^2=250000J$

Power $=\frac{250000}{10}=25000W=25KW$