Q. A 500 kg car, moving with a velocity of $36\ km\ h^{- 1}$ on a straight road unidirectionally, doubles its velocity in one minute. The power delivered by the engine for doubling the velocity is
A) 750 W
B) 1050 W
C) 1150 W
D) 1250 W
Explanation
(d) $u = 10ms^{- 1},v = 20ms^{- 1}$
Work done = increase in kinetic energy
$= \frac{1}{2} \times 500\left\lbrack 20^{2} - 10^{2} \right\rbrack = \frac{500 \times 30 \times 10}{2}$
$Power = \frac{500 \times 30 \times 10}{2 \times 60}W = 1250\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.