- #1
derrickb
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Before I ask the question, just want to say hi to everyone and introduce myself. Name's Derrick and I'm a sophomore engineering physics major at WPI. I'm currently in an Intermediate Mechanics course. Onto the problem:
A rocket in free space that starts at rest with total mass M ejects exhaust gas at a given speed u. What is the mass of the rocket(including unused fuel) when its momentum is maximum? What is the mass when its energy is maximum? [use E=.5mv^2 for energy]
Mv=P
E=.5mv2
v=v0+uln(m0/m) (maybe?)
Mv=0
-mexhaustu+(M-mexhaust)v=0
(M-mexhaust)v=mexhaustu
v=(mexhaust/(M-mexhaust))u
I'm stuck here. Do I take the derivative of v?
Homework Statement
A rocket in free space that starts at rest with total mass M ejects exhaust gas at a given speed u. What is the mass of the rocket(including unused fuel) when its momentum is maximum? What is the mass when its energy is maximum? [use E=.5mv^2 for energy]
Homework Equations
Mv=P
E=.5mv2
v=v0+uln(m0/m) (maybe?)
The Attempt at a Solution
Mv=0
-mexhaustu+(M-mexhaust)v=0
(M-mexhaust)v=mexhaustu
v=(mexhaust/(M-mexhaust))u
I'm stuck here. Do I take the derivative of v?