|Mar19-13, 06:38 PM||#1|
Rocket Burning fuel causing change in mass
I made up a scenario: Let's say I have a rocket at rest in space. The rocket initially weighs 100 kg, 50 kg of which is fuel. If the fuel burns at a constant rate of 1 kg/s and produces a thrust of 100 N out the back of the rocket, what will the rocket's velocity be after it runs out of fuel?
From F=ma and V=v0+at, I derived V=Ft/m. The force is 100 N, and it would take 50 s to burn 50 kg of fuel at 1 kg/s, so it would be V=100*50/m.
My question is: What would I use for the mass, since it is changing at the fuel burns? When I assumed that it was just the average mass, 75 kg, I got the final velocity ≈ 66.7 m/s. Am I supposed to just use the average mass since the fuel is burned at a constant rate? Does rocket fuel in the real world burn at a constant rate, or exponentially? If it was exponential, could I just use calculus to find the average mass and then plug it in?
|Mar19-13, 06:59 PM||#2|
|Mar19-13, 08:14 PM||#3|
|burn, fuel, rocket, thrust|
|Similar Threads for: Rocket Burning fuel causing change in mass|
|Rocket thrust, mass, speed given initial m and fuel consumption rate?||Introductory Physics Homework||4|
|Expelled rocket fuel pushing against something the rocket is attached to?||Classical Physics||7|
|Homework help finding fraction of initial mass of rocket and fuel||Introductory Physics Homework||3|
|Adding a mass on an oscillation causing a change in frequency||Introductory Physics Homework||5|
|Burning salt water for fuel?||General Discussion||81|