Question

When two objects with different temperatures are put in contact with each other, they both achieve
the same temperature after some time. Why is it so?

Answer 1

when two objects are in thermal contact with each other , temperature transfer takes place between them​.temperature transfer takes place only when two objects attain same temperature. this state is known as thermal equilibrium.

Answer 2

The objects will exchange thermal energy until their temperatures are equal.
Two objects at different temperatures when placed in contact will eventually come to the same temperature. It happens due to thermal equilibrium.