Question

an empty 20000kg coal wagon is moving 9n a level track of 5m/s suddenly 5000kg of coal is dumped into it from directly above.the coal initially has zero horizontal velocity. the final speed of wagon is

Answer 1

This is a question on conservation of linear momentum.

It states that :

Initial momentum = Final momentum.

Momentum = mass × Velocity

Initial momentum is :

(20000 × 5) + (5000 × 0) = 100000Kgms⁻¹

Final momentum = (20000 + 5000)V

= 25000V

25000V = 100000

V = 100000/25000

V = 4 m/s