A train whose weight is 20kN moves at the rate of 60km/hr. After brakes are applied, it is brought to rest at 500m. What is the force exerted, assuming it to be uniform?

Given:

Weight of the train:

$W=20\textup{ kN}$

Speed of the train:

$u=60\textup{ km/h}=16.667\textup{ m/s}$

Stopping distance:

$d=500\textup{ m}$

Write the equation of acceleration:

$a=\frac{u^2}{2d}=\frac{16.667^2}{2(500)}=0.278\textup{ m/s}^2$

Write the equation of the breaking force:

$F=\frac{Wa}{g}=\frac{20(0.278)}{9.81}=0.567\textup{ kN}$

Thus, the breaking force is 0.567 kN.

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