gravitational energy and internal energy So assume we have a planet of temperature T, and mass M, We can calculate it's internal energy/heat content by the formula $U=cMT$ where $c$ is the specific heat.

And if we also know the gravitational energy of the planet via $\frac{GM^2}{R}$  

how do I approach the following question?

Can the release of gravitational energy during planet formation in principle (is there enough) explain this much heat

Any help would be appreciated.
Can the release of gravitational energy during planet formation in principle (is there enough) explain this much heat


Planets in general can have internal heat sources (like radioactive breakdown or a complex hot core).  During planetary formation there are thought to be multiple collisions with large proto-planets before things settle down to a more-or-less stable set of orbits and planets.  These collisions add energy to the planets as they develop and increase temperature (a lot), as does ongoing bombardment from boring-old asteroids.

Now all of this energy does basically come from gravitational sources, but as you can see it's a complex (messy) business and there are many significant events that can alter temperature.

It might be instructive for you to read about existing theories on the formation of Solar system as well as material related to the structure of the Earth.