1. Grade 5 Heat Unit Review Questions

2. Why do substances that have been heated decrease in temperature over time? Where does the heat go? Substances will decrease in temperature over time because the heat moves towards the cooler surrounding air and surfaces. This causes a drop in temperature of the substance.

3. Explain expansion and contraction Expansion is the increase in volume of a substance as it is heated. Contraction is the decrease in volume of a substance as it is cooled. Expansion is the increase in volume of a substance as it is heated. Contraction is the decrease in volume of a substance as it is cooled.

4. How can expansion and contraction explain why roads crack in places that have both cold and hot seasons? As the seasons change and temperatures change, the cement sidewalks and asphalt roads expand and contract with the change in temperature. As the seasons change and temperatures change, the cement sidewalks and asphalt roads expand and contract with the change in temperature. Over time all of that expanding and contracting causes cracks in the roads and sidewalks because they are made from materials that are not meant to bend or move. Over time all of that expanding and contracting causes cracks in the roads and sidewalks because they are made from materials that are not meant to bend or move.

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

6. Which diagram of molecules has the most energy? The gas state has the most energy because the molecules are moving the fastest. The gas state has the most energy because the molecules are moving the fastest.

7. Match each example with the correct method of heat transfer. 1. A metal knife heats up because the end of it was left near a hot burner. 1. A metal knife heats up because the end of it was left near a hot burner. Conduction Conduction 2. A glider can fly using the hot air currents to keep it in the air. 2. A glider can fly using the hot air currents to keep it in the air. Convection Convection 3. The sun causes sun burns. 3. The sun causes sun burns. Radiation Radiation