What was the source(s) of the heat that made the early Earth much ...

[asan beg]

What was the source(s) of the heat that made the early Earth much hotter than it is today?
 
  What will be an ideal response?

Question 2

What is the process of planetary differentiation? How did this process determine the composition of Earth?
 
  What will be an ideal response?

[BUTTHOL369]

Answer to Question 1

Collisional heating and radioactive decay (including short-lived types).

Answer to Question 2

Earth began as a magma ocean, and it chemically differentiated into the core of iron- seeking elements, and the mantle, composed of lighter elements. Differentiation is the result of density variations, causing denser metals to sink and form the core while less dense silicates made up the mantle.