An eingine of power 58.8 kW pulls a train mass `2 xx 10^(5)` kg with a velocity of `36 kmh^(-1)`. The coefficient of friction is

Options

A. 0.3
B. 0.03
C. 0.003
D. 0.0003

Answer

C

Explanation

Power of engine,
`P = 58.8 kW = 58.8 xx 10^(3) W`
Mass of the train, `m = 2 xx 10^(5) kg`
Velocity of train, `v = 36 kmh^(-1)`
`= (36 xx 10^(3))/(60 xx 60) = 10 ms^(-1)`
Power, P=F.v
`therefore F = (P)/(v) = (58.8 xx 10^(3))/(10)`
= 5880 N
Let the coefficient of friction is `mu`.
`therefore F = f_(s) = mu mg`
`rArr mu = (F)/(mg) = (5880)/(2 xx 10^(5) xx 10)`
`= 0.003`