Question

A body of mass $2kg$ is being dragged with a uniform velocity of $2m/s$ on a rough horizontal plane. The coefficient of friction between the body and the surface is $0.20,J=4.2J/cal$ and $g=9.8m/s^2$. Calculate the amount of heat generated in $5sec$.

• A. 9.33 cal
• B. 19.33 cal
• C. 29.33 cal
• D. 39.33 cal

Answer 1

The correct option is A 9.33 cal

$m=2kg,v=2m/s,t=5sec$

$\mu =0.2$

$d=v\times t=2\times 5=10m$

As, $F=\mu N=\mu \left(mg\right)$

$=0.2\times 2\times 9.8$

$F=3.92N$

Work done $=F\times S=3.92\times 10$

$=39.2J$

This work done is stored in form of

heat energy

$\therefore$ Heat energy $=\frac{39.2}{4.2}cal$

$=9.3cal$