A wagon is moving along a straight railway track with a velocity of 3.2 `m cdot s^(-1)`. The wagon is being loaded with coal in moving condition at a rate of 540 kg.`min^(-1)`. How much force is to be applied to move the wagon at a constant velocity?Assume, the initial velocity of the coal at horizontal direction is zero.

Explanation

The velocity of the wagon,
v = 3.2 m`cdot s^(-1)`
and the rate of change of mass of the wagon,
`(dm)/(dt) = 540 kg cdot min^(-1) = (540)/(60) kg cdot s^(-1) = 9 kg cdot s^(-1)`
Hence, force to be applied on the wagon to maintain its constant velocity (acceleration, a = `(dv)/(dt)` = 0 ) .
`F = v(dm)/(dt) + m(dv)/(dt) = 3.2 xx 9 + 0 = 28.8` N