Question

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

Answer 1

Answer: (A)

3.75 J

Answer 2

According to energy conservation, change in kinetic

energy appears in the form of heat (thermal energy).

⇒ i.e. Thermal energy $= \frac{1}{2}m(v_{1}^{2} - v_{2}^{2})$ $\left\lbrack \because\underset{(\text{Joule})}{W} = \underset{(\text{Joule})}{Q} \right\rbrack$

$= \frac{1}{2}(100 \times 10^{- 3})(10^{2} - 5^{2}) = 3.75J$