Transfer of Thermal Energy

In a very common classroom Physics demonstration, a teacher sets up a rod, as shown in the diagram. Half of the rod is copper, the other half is wood.

She sticks four lead balls to the rod using wax. The wax melts when its temperature rises a small amount, causing the ball to fall off.

The teacher heats the rod in the center, with something more gentle than a Bunsen burner, that will not burn the wood.

Which ball falls off first?

• A

• B

• C

• D

Which of the following processes take place in a non-metal to allow the conduction of thermal energy?

• A

• B

• C

• D

A family goes on a picnic and they want their food to stay cold.

In order to achieve this, they put two ice packs with the picnic food in a hamper.

Where should both ice packs be placed in order to keep the food as cool as possible?

• Both at the top of the hamper

• One at the top of the hamper and one at the bottom

• Both at the bottom of the hamper

• On either side of the hamper

Which states of matter can convention happen in?

• solids and liquids

• liquids and gases

• gases and solids

• solids, liquids and gases

Hot fluids rise. This can be explained because, as the fluid gets hotter, there is a decrease in the fluid’s:

• mass

• temperature

• density

• volume

What is the definition of CONDUCTION?

• 
  When heat is transferred from objects like rays of light or electromagnetically.

• a  hot liquid or air that  expands, becomes less dense, and rises or becomes more dense, and sinks.

• When heat transfers from objects that are touching.

• 
  When heat transfers through the heater or AC in your house.

Which best describes the process of convection?

• Convection is the primary way  heat travels  through rays.

• Convection is the primary way heat travels  through metals.

• Convection is the primary way heat travels  through appliances.

• Convection is the primary way heat travels  through liquids and gasses.

What is the relationship between temperature and density in convection?

• As temperature decreases, density increases

• As temperature increases, density decreases

• As temperature increases, density increases

• As temperature decreases, density decreases

How does convection affect the movement of materials in the Earth's oceans?

• 
  It has no effect on the movement of materials

• It causes water to sink at the equator and rise at the poles

• It causes water to sink at the poles and rise at the equator

• It causes water to move in a circular motion

Which of the following is NOT an example of convection in everyday life?

• Boiling water in a pot

• A hot air balloon rising

• A fan blowing cool air

• A lava lamp