Question

How does thermal equilibrium affect heat transfer?

Answer 1

Every time molecules collide, kinetic energy can be transferred. When the two systems are in contact, heat will be transferred through molecular collisions from the hotter system to the cooler system. The thermal energy will flow in that direction until the two objects are at the same temperature.

According to

${\bf{\underline{Zeroth\: law\: of\: thermodynamics}}}$

When two objects are placed in contact heat (energy) is transferred from one to the other until they reach the same temperature (are in thermal equilibrium). When the objects are at the same temperature there is no heat transfer.