Grade 5 Heat Unit Grade 5 Heat Unit Review QuestionsReview Questions

Why do substances that have been heated Why do substances that have been heated decrease in temperature over time? Where decrease in temperature over time? Where

does the heat go?does the heat go?

Substances will decrease in temperature over Substances will decrease in temperature over time because the heat moves towards the time because the heat moves towards the cooler surrounding air and surfaces. cooler surrounding air and surfaces.

This causes a drop in temperature of the This causes a drop in temperature of the substance.substance.

Explain expansion and contractionExplain expansion and contraction

Expansion is the increase in volume of a Expansion is the increase in volume of a substance as it is heated. Contraction is the substance as it is heated. Contraction is the decrease in volume of a substance as it is decrease in volume of a substance as it is cooled.cooled.

How can expansion and contraction explain why How can expansion and contraction explain why roads crack in places that have both cold and hot roads crack in places that have both cold and hot

seasons?seasons?

As the seasons change and temperatures As the seasons change and temperatures change, the cement sidewalks and asphalt change, the cement sidewalks and asphalt roads expand and contract with the change in roads expand and contract with the change in temperature. temperature.

Over time all of that expanding and Over time all of that expanding and contracting causes cracks in the roads and contracting causes cracks in the roads and sidewalks because they are made from sidewalks because they are made from materials that are not meant to bend or move.materials that are not meant to bend or move.

Describe how the molecules of a substance Describe how the molecules of a substance might look in a solid, liquid and gas state.might look in a solid, liquid and gas state.

Which diagram of molecules has the Which diagram of molecules has the most energy?most energy?

The gas state has the most energy because the The gas state has the most energy because the molecules are moving the fastest.molecules are moving the fastest.

Match each example with the correct Match each example with the correct method of heat transfer.method of heat transfer.

1. A metal knife heats up because the end of it 1. A metal knife heats up because the end of it was left near a hot burner.was left near a hot burner.

ConductionConduction 2. A glider can fly using the hot air currents to 2. A glider can fly using the hot air currents to

keep it in the air.keep it in the air. ConvectionConvection 3. The sun causes sun burns.3. The sun causes sun burns. RadiationRadiation