What causes thermal expnsion?

Answer: Thermal expansion occurs when an object expands and becomes larger.

Explanation: This occurs when a change (increase or decrease)

Forms in an objects temperature

For example, Increase in size of a material due to added heat.

Decrease in size of material when heat is removed.

Thermal expansion occurs when an object expands and becomes larger due to a change in that specific object's temperature. Temperature is the average kinetic (basically movement) energy of the molecules in a substance. A higher temperature means that the molecules are moving faster on average.