Gravitational Acceleration (Gauss law)

[moknight]

Homework Statement

Homework Equations

Just to clarify the question, the value given for R2 is the overall radius of Earth, it isn't R1-R2. (At least, that's my interpretation given that the R2 value is approx. the Earth's radius)

The Attempt at a Solution

Don't really know how to go about it, the approach I've tried is to use the given densities and volumes (from the radii) to find the mass of the core and the mantle. Added the masses (it computes to half the Earth's mass ) and then used
g = GM/(R^2).

I'm getting g = 4.1 for part i)

All help would be much appreciated!

Thanks :)

 

[andrien]

at least show me your problem