Question

A train of weight $10^7\ N$ is running on a level track with uniform speed of ${36\, km\, h^{-1}}$. The frictional force is 0.5 kg f per quintal. If $g ={ 10 \, m \, s^{-2}}$, power of engine is

• A. 500 kW
• B. 50 kW
• C. 5 kW
• D. 0.5 kW

Answer 1

Answer: (A)

500 kW

Answer 2

Weight of train = ${10^7 \, N = 10^6\, kg\, f}$
Frictional force, $F = \frac{0.5}{100} \times 10^6 = 5000 \, { kg \, f}$
$F = 50000 \, N$
$v ={ 36 km \, h^{-1} = 10 \, m \, s^{-1}}$
$P = F \times v = {50000 \times 10 = 5 \times 10^5 \, W = 500 \, kW }$