return to
What's Current

Exploring Heat and Density:

The Big Ideas about Heat

Focus Question: What is heat?

Heat is a form of energy produced by different sources.
Sources of heat include:

• the sun

• the Earth’s core

• chemical reactions

• radioactivity

• friction

Focus Question: What happens when the amount of heat changes?

A. Adding heat:

• causes molecules to move more quickly to most liquids and gases

• causes them to expand - become less dense

B. Removing heat:

• causes molecules to move more slowly from most liquids and gases

• causes them to contract – become more dense

C. Adding or removing heat can change the state of a gas, liquid, or solid.

Focus Question: How does heat travel?

A. Conduction

• Heat travels differently through materials by conduction.

• Some materials are better conductors than others.

• The transfer of heat by direct contact of particles of matter causes molecules to move more quickly.

B. Convection Heat travels through fluids by convection. The transfer of heat between warmer and cooler gases and liquids creates currents.

Return to: What's Current | Dynamic Earth Homepage | UCMP Homepege