# Homework Help: Rocket performance

1. Feb 22, 2010

### strttnr

what equation would i use to find the max velocity and max alt of a rocket. the probem gave me mass of rocket (g), mass of engine (g), mass of propellant (g), average thrust of engine(newtons), burn duration of the engine (seconds). i got an example which is massrocket=23,mass engin=16.2,massproppelant=3.12, averagethrust=8 and burndurationengine=.5

their max vel=101.37 and max alt = 549.621

it gave me some equations which are x=x0+vt , v=v0+at , x=x0+v0t+.5at"square" and f=ma
(x=distance,v=velocity, t=time, a= acceleration, f=force, m=mass and 9.8 as grav m/s"square

i need better understanding of what information goes where plug in to equation
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Feb 22, 2010

### Staff: Mentor

The simplest thing would be to go to wikipea.org and search on Rocket Equation. That will give you plenty of information to read. Seems like it should also be in your textbook, but maybe they want you to do some outside reading...

Welcome to the PF, BTW.

3. Feb 22, 2010

### strttnr

thanks ...but this is just a problem for computer progamming but i dont even got a txt book to rely on to get help and i tried wiki and the way they explain it is too technical and confusing.. is there anywhere else or possibly give a link or explain to me in simplest terms on how to go about this problem using the example provided

4. Feb 22, 2010

### jwxie

This is just a bit more works than a simple projectile motion. Just remember there are two things to consider

1. gravity (g or -g)
2. engine also causes a kind of acceleration

it is very difficult to read your post, words become "compounds"

state the entire problem using the given posting format. this helps readability
and of course, search around google

5. Feb 22, 2010

### Staff: Mentor

The other part of the Rocket Equation takes into account that the rocket becomes lighter as it burns off fuel...

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