Q. 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 $g = 10, ms^{- 2}$, power

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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 $g = 10, ms^{- 2}$, power

Solution:

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 $

$5 times 10^5 times 10^5 ,W$

$ = 500,kW$.