4.4 thermal energy answers

In some places, hot water from underground can shoot up into the air through a hole in the ground. When this happens, the ground surrounding the water increases in temperature. What happens to the molecules in the ground when the temperature of the ground increases?

• More heat molecules combine with the molecules in the ground.

• The energy of the molecules in the ground decreases.

• The energy of the molecules in the ground increases.

• The cold energy of the molecules in the ground decreases.

In some places, hot water from underground can shoot up into the air through a hole in the ground. When this happens, the ground surrounding the water increases in temperature. What happens to the molecules in the ground when the temperature of the ground increases?

• More heat molecules combine with the molecules in the ground.

• The energy of the molecules in the ground decreases.

• The energy of the molecules in the ground increases.

• The cold energy of the molecules in the ground decreases.

A space shuttle is covered with two layers of carbon. The two layers are the same size and have the same number of molecules. When the space shuttle is sitting on the ground, the layers do not touch, as shown in the diagram above. When the space shuttle takes off, the layers move so that they are touching. Use the information in the diagram to answer the question.

How does the temperature of the outer layer compare with the temperature of the inner layer before the layers touch? What will happen after the layers have been touching for a while?

• Before the layers touch, the outer layer is hotter than the inner layer. Once the layers are touching, the outer layer will transfer kinetic energy to the molecules in the cooler inner layer until both layers reach the same temperature, which will be in between their starting temperatures.

• Before the layers touch, the outer layer is hotter than the inner layer. Once the layers are touching, the cooler inner layer will gain kinetic energy until the molecules of both layers have an energy of 90, because hotter things increase the temperature of cooler things.

• Before the layers touch, the outer layer is cooler than the inner layer. Once the layers are touching, the inner layer will transfer kinetic energy to the molecules in the cooler outer layer until both layers reach the same temperature, which will be in between their starting temperatures.

• Before the layers touch, the layers are different temperatures. Once the layers are touching, kinetic energy and cold energy will transfer between the molecules in the two layers until both layers reach the same temperature, which will be in between their starting temperatures.