Conservation of momentum rocket question (2 Viewers)

[clintmyster]

Consider a rocket with a mass of 50000kg moving at 100m/s. The rocket motor ejects a 1000kg "burst" of gas every 10 seconds with a velocity of 1000m/s. What is the velocity of the rocket relative to the Earth after 10s?

answer is like 120.41m/s

any ideas?

 

[undalay]

Momentum of expelled gases = momentum gained by ship.

Momentum of expelled gasses = 1000x1000 = 1,000,000

1,000,000 = momentum gained by ship
1,000,000 = 49 000 x V (50,000kg - 1000kg from expelled gases)
V = 20.41

total velocity = initial velocity + velocity gained
=100+20.41
=120.41