Gr. 7 - Heat - Thermal Expansion & Contractio

What happens to the metal sphere after it’s heated with a blowtorch?

• It becomes smaller and fits through the ring easily

• It expands and no longer fits through the ring

• It melts and sticks to the ring

• It stays exactly the same size

Why does the metal sphere expand when heated?

• The particles vibrate slower and move closer together

• The particles stop moving

• The particles gain kinetic energy and push farther apart

• The particles lose energy and shrink

What is the term used to describe the increase in size when a material is heated?

• Heat transfer

• Thermal contraction

• Thermal expansion

• Particle separation

What happens during thermal contraction?

• Particles speed up and move apart

• Particles slow down and move closer together

• Particles vibrate faster

• The material gains kinetic energy

Why do sidewalks have gaps or lines built into them?

• To make them look more decorative

• To prevent flooding

• To let water drain through

• To allow for thermal expansion and contraction

When a liquid like water is heated, what happens to its volume?

• The volume decreases

• The volume stays the same

• The volume increases due to thermal expansion

• The liquid evaporates immediately

How does a thermometer use thermal expansion?

• The liquid expands in heat and rises, or contracts in cold and falls

• The glass expands and changes color

• The thermometer creates its own heat

• The particles in the thermometer stop moving

Why is thermal expansion a concern for coastal regions?

• It causes stronger winds

• It increases ocean salinity

• It makes the water freeze faster

• It makes the sea level rise and increases flooding risk

When a gas is heated, what happens to the particles?

• They lose energy and slow down

• They gain kinetic energy and push harder against surfaces

• They become solid

• They disappear from the container

How does heating the air in a hot air balloon make it rise?

• The air becomes denser and sinks

• The air expands, becomes less dense, and floats upward

• The balloon fills with cold air

• The particles stop moving