Question

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

• A. 20 KW
• B. 25 KW
• C. 30 KW
• D. 35 KW

Answer 1

The correct option is B

25 KW

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 the change in kinetic energy of the car and the time taken for that change would give us the power developed by the engine i.e.
Work done $=\frac{1}{2}m{v}^2=\frac{1}{2}\times 50\times {100}^2=250000J$

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