(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Assuming that we know the density of earth as a function of radius, we have to derive the equation for gravity as the function of radius.

2. Relevant equations

3. The attempt at a solution

lets us choose density as [tex]\rho[/tex](r).

I know that within a hollow sphere there is no gravity.

We can assume sum of several hollow spheres with thickness dr, where r is the radius of the shell from center, and then we can integrate it.

I know its an easy question we used to do in undergraduate study, but I am missing something and i cant figure out how it was done? Please help!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Gravitation (Preliminary Reference Earth Model)

**Physics Forums | Science Articles, Homework Help, Discussion**