You're on the right track! When two substances at different temperatures come into contact, heat will transfer from the warmer substance to the colder substance.

Here's why:

* Heat is a form of energy. It always flows from an area of higher energy to an area of lower energy.

* Temperature is a measure of the average kinetic energy of the particles within a substance. Warmer substances have particles moving faster and therefore have higher kinetic energy.

* When substances with different temperatures come in contact, the particles in the warmer substance collide with the particles in the colder substance. This collision transfers energy, causing the colder substance to warm up and the warmer substance to cool down.

This process continues until both substances reach thermal equilibrium, meaning they have the same temperature.