Q. A block of mass $100\ gm$ slides on a rough horizontal surface. If the speed of the block decreases from $10\ m/s$ to $5\ m/s,$ the thermal energy developed in the process is
A) $3.75\ J$
B) $37.5\ J$
C) $0.375\ J$
D) $0.75\ J$
Explanation
(a) According to energy conservation, change in kinetic energy appears in the form of heat (thermal energy)
$\Rightarrow i.e.$ Thermal energy $= \frac{1}{2}m\left( v_{1}^{2} - v_{2}^{2} \right)\left\lbrack \because\begin{matrix}
W \\
(Joule)
\end{matrix} = \begin{matrix}
Q \\
(Joule)
\end{matrix} \right\rbrack$
$= \frac{1}{2}\left( 100 \times 10^{- 3} \right)\left( 10^{2} - 5^{2} \right) = 3.75J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.