A rocket for use in deep space is to have the capability of boosting a pay load ( plus the rocket frame and engine) of 3 metric tonnes to an achieved speed of 10000m/s with an engine and fuel designed to produce an exhaust velocity of 2000m/s.
a) How much fuel and oxidizer is req'd, b)and if a diff fuel and engine design could give an exhaust velocity of 5000m/s, what amount of fuel and oxzidier would be req'd?
The Attempt at a Solution
m1 = 3000 kg, v1= 0, v1' = 10 000m/s
m2 = ? kg, v2 = 0, v2' = 2000m/s
m1v1 + m2v2 = m1v1' + m2v2'
0 = m1v1' + m2v2'
-m1v1' / v2'= m2
-15 000 kg = m2
How is the mass negative :S
the answer at the back says "442 x 10^3 kg"
so I know I'm off by a lot... Our fizzicks teacher didn't teach us how to solve these problems, but I assumed it was a momentum problem.
Any help would be greatly appreciated. :)