Q. A body of mass $2\ kg$ is being dragged with uniform velocity of $2\ m/s$ on a rough horizontal plane. The coefficient of friction between the body and the surface is 0.20. The amount of heart generated in $5\ sec$ is $(J = 4.2\ joule/cal$ and$\ g = 9.8\ m/s^{2})$
A) $9.33\ cal$
B) $10.21\ cal$
C) $12.67\ cal$
D) $13.34\ cal$
Explanation
(a) Work done = Force $\times$ displacement $= \mu\ mg \times (v \times t)$
$W = (0.2) \times 2 \times 9.8 \times 2 \times 5\ joule$
Heat generated $Q = \frac{W}{J} = \frac{0.2 \times 2 \times 9.8 \times 2 \times 5}{4.2} = 9.33\ cal$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.