Explain why the sun does not collapse under the force of its own gravity

It is only because the inner parts of the Sun are hotter that the Sun doesn't collapse under its own gravity. The atoms in the central regions move faster than those in outer regions and consequently they push outwards with more force, holding the Sun up.

Explanation:

Gravity constantly works to try and cause the star to collapse. The star's core, however is very hot which creates pressure within the gas. This pressure counteracts the force of gravity, putting the star into what is called hydrostatic equilibrium.

found in the nucleus

has mass of one amu

3.2x10^7