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Standard XII

Physics

The 'e' Equation

A train of ma...

Question

A train of mass $10^{4} k g$ is moving on a level track at a uniform speed of 72 km/hr. If the coefficient of friction is 0.25, find the power of its engine ( $g = 9.8 m / s^{2}$ )?

980 kW

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490 kW

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245 kW

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790 kW

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Solution

The correct option is B 490 kW
We know that:
$P = F . v$
$F = μ m g$
$= 0.25 \times 10^{4} \times 9.8$
Also, velocity, $v = 72 k m p h = 20 m / s$
$∴ P = 0.25 \times 9.8 \times 10^{4} \times 20$
$∴ P = 490 k W$

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A train of mass 104kg is moving on a level track at a uniform speed of 72 km/hr. If the coefficient of friction is 0.25, find the power of its engine (g=9.8m/s2)?

The correct option is B 490 kWWe know that:P=F.vF=μmg=0.25×104×9.8Also, velocity, v=72kmph=20m/s∴P=0.25×9.8×104×20∴P=490 kW

A train of mass $10^{4} k g$ is moving on a level track at a uniform speed of 72 km/hr. If the coefficient of friction is 0.25, find the power of its engine ( $g = 9.8 m / s^{2}$ )?

The correct option is B 490 kW
We know that:
$P = F . v$
$F = μ m g$
$= 0.25 \times 10^{4} \times 9.8$
Also, velocity, $v = 72 k m p h = 20 m / s$
$∴ P = 0.25 \times 9.8 \times 10^{4} \times 20$
$∴ P = 490 k W$