# Homework Help: Atmospheric density calculation (of mars)

1. Jan 20, 2010

### blackdog666

1. The problem statement, all variables and given/known data

gravitational constant G=6.67x10^-11 Nm^2/Kg^2, M=6.42x10^23 Kg, and R=3.40x10^6 m for mars. Calculate the atmospheric density of Mars.

2. Relevant equations

Density of water = 1000 Kg/m^3
Atmospheric pressure = 30 Pa (from what i've calculated)

p=M/V

3. The attempt at a solution

I just don't know where to start. I'm completely lost. I've looked at formulas online, however they all deal with temperature, and I'm 100% positive I don't need any temperature values for my calculation.

Last edited: Jan 20, 2010
2. Jan 20, 2010

### cepheid

Staff Emeritus
Hi blackdog666, welcome to PF

I'm confused about what your problem is asking. Your thread title says it has to do with the "atmospheric density" of Mars, but the actual problem statement that you have posted in thread just says, "calculate the density of Mars."

A simplistic approach to the problem would be to just compute the average density, or in other words the density you would get if you have a totally uniform solid sphere. This is just given by the total mass over the total volume. You know the mass and would just have to calculate the volume.

I think you need to clarify what your problem is asking before anyone can advise you further on the best way to proceed.

3. Jan 20, 2010

### blackdog666

Oh, sorry I meant to say calculate the atmospheric density.

4. Jan 20, 2010

### cepheid

Staff Emeritus
Hmm...well that's weird because your problem doesn't give you any information about Mars' atmosphere. Not only that, but the density of the atmosphere will not be constant but will change with height (due to gravity), just like on Earth.

5. Jan 20, 2010

### blackdog666

Yeah. I'm really confused. I'll ask my teacher the next time I see her, and see if maybe she left out some information.

6. Jan 20, 2010

### lizick

next ?
You 'd better send her a letter to ask for an appointment
or read her website for office hours then DO it right today NOT next!
I believe this is a very good way to learn and be beeter btter
By the way your username sours the truthful relationship with me for the most part of my petlife I love all pets my latest black dog is truthful and clearly open than my hens

7. Jan 20, 2010

### cepheid

Staff Emeritus
Well, that would certainly be true if the OP were chasing down a university prof, since they are notoriously busy. However, for all we know, the OP could be in high school, in which case he is guaranteed to see his teacher in class on a regular basis, and his class size is small enough that he can probably get one-on-one help with a problem if he tells the teacher before or after class. I think its pretty funny to just assume that OP is being apathetic when you don't have any information.