Q 11-05-106JEE MainJEE Main 2023 (12 Apr, Shift 1)Easy
To maintain a speed of $80\ \text{km h}^{-1}$ by a bus of mass $500\ \text{kg}$ on a plane rough road for $4\ \text{km}$ distance, the work done by the engine of the bus will be ______ kJ. [The coefficient of friction between tyre of bus and road is $0.04$]
Numerical value type. Enter your answer.
Answer: 784
At constant speed the engine force equals friction, $\mu mg$. Taking $g=9.8\ \text{m s}^{-2}$:
$$W=\mu mg\,d=0.04\times500\times9.8\times4000=784000\ \text{J}=784\ \text{kJ}$$
Solution by Sreeraj P, M.Sc Physics