Assessment

=—Assessment=

Section 1
1. Explain how energy moves when you touch a block of ice with your hand. Thermal Energy from your hand is transferred to the ice and makes it melt.

2.Describe how the thermal energy of an object changes when the objects temperature changes. When temperature changes, thermal energy changes with it.

3. Infer: When heat flows between two objects, does the temperature increase of one object always equals the temperature decrease of the other object? Explain. No, the temperature change depends on the specific heat of each material.

4. Explain why the specific heat of water is higher than the specific heat of most other substances. Molecules of water has stronger bonds between them which acquires more thermal energy to heat the water.

5. Expalin whether or not the following statement is true: for any two objects, the one with the highter temperatue always has more thermal energy. False, it depends on the amount of the material in the object and the potential energy of the particles in the object.

Section 2
1.Explain why materials that are good conductors of heat are poor insulators. Metals that are good conductors of heat are poor insulators. Because in these metals, heat flows more rapidly from one place to another.

2.Explain why the air temperature near the ceiling of a room tends to be warmer than near the floor. Heat naturally rises.

3. Predict whether plastic foam, which contains pockets of air, would be a good conductor or a good insulator. It would be an alright insulator because it would hold in heat and not let cool air in, the air pocket might become warm or not.

4.Describe how a convection current occurs. Convection currents transfer heat from warmer to cooler parts of the fluid. In a convection current, both conduction and convection transfer thermal energy.

5.Think critically, several days after a snowfall, the roofs of some homes on a street have almsot no snow on them, while the roofs of other houses are sill snowcovered. Descirbe what would cause this difference. The shingles on the house would determine some of the difference. Warmer houses would have less snow because of the warmth.

Section 3
1.Explain how the thermal energy of a closed system changes with time. The energy will become potential energy and the temperaure will cool.

2.Compare and contrast an active solor heating system with a radiator system. In radiator heating systems fuel burned in a central furnace heats a tank of water, a system of pipes carries the hot water to radiators in the rooms of the building. An active solar heating system absorbs radiant energy from the sun in solar collectors, the sun shines into the collectors and then, for some collectors, heats the water and sends the heated water to radiators throughout the house.

3.Explain whether or not a heat engine could be made 100 percent efficient by eliminating friction. No, the engine would not have 100% efficiency, instead the efficiency of an internal combustion engine depends on the difference of the burning gases in the cylinder and the temperature of the air outside the engine.

4.Diagram how the thermal energy of the coolant changes as it flows in a refrigerator.

5.Think Critically Suppose you vigorously shake a bottle of fruit juice. PRedict how the termperature of the juice will change. Explain your reasoning.