Summary of Heat Effects on Matter

Effects of Heat on Matter

Change in Temperature

• Heat supplied to a substance increases its temperature.

• Heat loss from a hot object decreases its temperature.

Change in Dimensions (Thermal Expansion)

• Increasing temperature causes length, area, and volume to increase (thermal expansion).

• Cooling causes substances to contract and decrease in size.

• Important in engineering to prevent structural damage.

Expansion in Solids

• Solids expand in three ways:   - Linear expansion: increase in length   - Superficial expansion: increase in area   - Cubical expansion: increase in volume

• Applications:   - Iron rims heated to fit wheels tightly when cooled.   - Gaps in railway tracks allow for heat expansion.   - Glass tumblers may crack when hot liquids are poured due to uneven expansion.

Expansion in Liquids

• Liquids have fixed volume but not fixed shape; mainly exhibit cubical expansion.

• Applications:   - Thermometers utilize expansion of mercury/alcohol.   - Heated liquids like milk overflow due to expansion.   - Containers left with space to allow for liquid expansion.

Expansion in Gases

• Gases expand the most when heated; no fixed shape or volume.

• Applications:   - Hot air balloons rise due to heated air expanding and becoming lighter.