Question

A rocket is ejecting 50g of gases per second at a speed of 500m/s. What is rocket force?

Answer 1

Here,

∆m/∆t = 50g/s = 0.05 kg/s

u = 500 m/s

Then by momentum conservation

m∆v  = -u∆m

dividing both sides by ∆t

m∆v/∆t = -u∆m/∆t

=> F = - 500×0.05

=> F = -25 N

-ve sign implies force given by the exhaust acts opposite to the direction of the velocity of the ga