# Homework Help: Rocket nozzle pressure of CO2

1. May 17, 2007

### Spiewgels

1. The problem statement, all variables and given/known data
Initial mass of the rocket is M = 30 x 10^3 kg, while its initial acceleration a = 3g. The rocket has four nozzles of diameter D = 20 cm each. Burning fuel leaves the nozzle with velocity v = 2.0 km/s having temperature T = 600◦C. Assuming fuel is burned completely and the exhaust gas is carbon dioxide CO2, determine its pressure P at the nozzle exit. Neglect air resistance.

2. Relevant equations
What is the best way to approach this problem? Most of the time I can get the problem started because I know what I'm dealing with in terms of what chapter the topic came from. I'm thinking I'm going to have to do something with the ideal gas law but I was told the problem would not have to worry about degree of freedom. I just need a booster so I can begin to work something out. (Thanks again to the last guys who helped me)

3. The attempt at a solution
Unfortunately, this is one of the few times I had nothing to start with. All I figured out thus far is that I will need to know that CO2 is 44g/mol.

2. May 17, 2007

### Dick

You know the acceleration of the rocket and you know the speed of the exhaust. From this you should be able to compute the mass of exhaust leaving the rocket per second. Since you know the speed of the exhaust and the area through which it passes, this should let you compute the density of the exhaust. Then you are basically where you can start applying what you've figured out so far.

3. May 17, 2007

### Spiewgels

ok, i'll get started on it right away...won't get home off the bus for 2 hours so if you happen to be up check out some of the pending work