Protoplanets of the Jovian planets could have grown very hot from
A) heat for the sun.
B) radioactivity of light elements such as hydrogen and helium.
C) the infall of material at high velocity.
D) tidal forces due to the sun.
E) collisions with large planetesimals.

Question

Quizplus · Accepted Answer

The infall of material at high velocity would generate a large amount of kinetic energy, which would convert to heat as the protoplanet grows. This process is known as accretion heating. The other choices may contribute to heating as well, but not to the same extent as the infall of material.

Protoplanets of the Jovian Planets Could Have Grown Very Hot