Question

a rocket ship in outer space has a mass of 650kg , including 120kg of fuel, and it is going 140m/s.Burning all the fuel produces a thrust of 1200N for 25s.How fast is the ship then going?

Answer 1

The impulse applied to the ship is

P = F dt = (1200 N) (25 s) = 30,000 N . s

And this must equal the increase in the momentum of the ship. Its original momentum is

mv = (650 kg) (140 m/s) = 91 000 kg.m/s