Question

A train of weight $10^{7} N$ is running on a level track with uniform speed of $36 \,kmph$. The frictional force is $0.5\, kg$ wt per quintal. If $a=10\, ms ^{-2}$, power of engine is

• A. 5 kW
• B. 0.5 kW
• C. 60 kW
• D. 500 kW

Answer 1

Answer: (D)

Weight of train, $w=10^{7} N=m a=m \times 10$
mass of train, $ m =10^{6} kg $
friction $=\frac{0.5 kg }{100}=\frac{0.5}{100} \times 10^{6}=5000\, kg $
$F =5000 \times 10$
$=5 \times 10^{4} N$
Power, $ P=F \times v =5 \times 10^{4} \times 10$
$=5 \times 10^{5} W $
$=500 \,kW$