Question

A metallic block of mass $20kg$ is dragged with a uniform velocity of $0.5m{s}^{-1}$ on a horizontal table for $2.1s$. The coefficient of static friction between the block and the table is 0.10. What will be the maximum possible rise in temperature of the metal block, if the specific heat of the block is 0.1 C.G.S. unit? Assume $g=10m{s}^{-1}$ and uniform rise in temperature throughout the whole block. [Ignore absorption of heat by the table]

• A. $0.0025{}^{o}C$
• B. $0.0035{}^{o}C$
• C. $0.001{}^{o}C$
• D. $0.05{}^{o}C$

Answer 1

The correct option is A $0.0025{}^{o}C$

$W=FS=\left(\mu mg\right)vtW=0.1\times 20\times 10\times 0.5\times 2.1=21J$

This work done by friction is converted into heat energy:
$\therefore Q=21JQ=20\times {10}^3\times 4200\times \Delta \theta$
$[asS=0.1\times 4200J/kg-K]$
$\Rightarrow \Delta \theta =0.0025K=0.0025{}^{o}C$