Question

The pictures below show the particles of two substances with different energies.



What will happen if the two substances are put into contact in an isolated system?

a
The energy in the system will transfer from substance A to B until equilibrium is reached.
b
The energy in the system will eventually increase as energy is created.
c
The energy in the system will eventually be destroyed.
d
The energy in the system will transfer from substance B to A until equilibrium is reached.

Answer 1

a

Energy flows from the higher-energy (hotter) substance to the lower-energy (colder) one until thermal equilibrium is reached. In an isolated system total energy is conserved (no creation or destruction).