JAMB Physics 2022 Paper

Concept:Power is the rate at which work is done, and for a moving train it can be found from the force that accelerates it multiplied by its final speed.Explanation:Assume the train starts from rest, so initial speed is $0 \, \text{m s}^{-1}$.Acceleration, $a = \frac{\Delta v}{t} = \frac{25}{20} = 1.25 \, \text{m s}^{-2}$.Force produced by the engine, $F = ma = 1600 \times 1.25 = 2000 \, \text{N}$.Power developed at the attained speed is $P = Fv$.Therefore, $P = 2000 \times 25 = 50000 \, \text{W}$.Convert to kilowatts: $P = \frac{50000}{1000} = 50 \, \text{kW}$.Answer:$50 \, \text{kW}$ (Option D).