Q. A car of mass ‘$m$’ is driven with acceleration ‘$a$’ along a straight level road against a constant external resistive force ‘$R$’. When the velocity of the car is ‘$V$’, the rate at which the engine of the car is doing work will be
A) $RV$
B) $maV$
C) $(R + ma)V$
D) $(ma - R)V$
Explanation
(c) Force required to move with constant velocity
$\therefore$ Power$\ = FV$
Force is required to oppose the resistive force $R$ and also to accelerate the body of mass $m$ with acceleration $a$
$\therefore$ Power $= (R + ma)V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.