Question 1

Which of the following best explains why sweating cools the human body?

Accepted Answer

Evaporation of sweat absorbs energy from the skin, lowering its temperature.

Question 2

A pressure cooker allows food to cook faster because:

Accepted Answer

The increased pressure raises the boiling point of water, allowing food to cook at a higher temperature.

Question 3

Which process is responsible for the formation of frost on a cold window during winter?

Accepted Answer

Condensation followed by freezing

Question 4

Why does steam cause more severe burns than boiling water at the same temperature?

Accepted Answer

Steam releases additional energy when it condenses on the skin.

Question 5

Which of the following phase changes requires the most energy per gram for water?

Accepted Answer

Vaporizing liquid water to steam

Question 6

What happens to the temperature of a substance while it is melting?

Accepted Answer

It remains constant until all the substance has melted.

Question 7

A can of soda is wet on the outside after being taken from the refrigerator into warm air. This is due to:

Accepted Answer

Condensation of water vapor from the air onto the cold can.

Question 8

Which of the following best describes the energy changes during the freezing of water?

Accepted Answer

Energy is released to the surroundings as water molecules form a solid structure.

Question 9

Why does water boil at a lower temperature in Denver, Colorado, than at sea level?

Accepted Answer

Atmospheric pressure is lower at higher altitudes, so water boils at a lower temperature.

Question 10

Which of the following statements about boiling is correct?

Accepted Answer

Boiling is a cooling process because energy is used to change liquid to vapor.

Question 11

A farmer places tubs of unfrozen water in a cellar to prevent jars of food from freezing. This works because:

Accepted Answer

The water releases energy as it freezes, warming the surrounding air.

Question 12

Which process is responsible for the direct transition from solid to gas, as seen with dry ice?

Accepted Answer

Sublimation

Question 13

When snow forms in clouds, what happens to the surrounding air?

Accepted Answer

It is warmed because energy is released during the phase change from gas to solid.

Question 14

Which of the following best describes the energy transfer in a refrigerator's cooling cycle?

Accepted Answer

Heat is absorbed from inside the fridge during vaporization and released outside during condensation.

Question 15

How much energy is required to melt 10 grams of ice at $$0^\circ \mathrm{C}$$? (Heat of fusion for water is $$334 \ \mathrm{J/g})$$

Accepted Answer

$$3340 \ \mathrm{J}$$

Question 16

Which of the following involves the greatest number of calories for 1 gram of water?

Accepted Answer

Condensing $$1 \ \mathrm{g} of$$ $$100^\circ \mathrm{C}$$ steam to $$100^\circ \mathrm{C}$$ water

Question 17

Why is it important for ice to melt in a picnic cooler to speed up the cooling of beverages?

Accepted Answer

Melting absorbs a large amount of energy (latent heat), cooling the beverages more effectively.

Question 18

Which of the following is true about the direction of energy flow during phase changes?

Accepted Answer

Energy is absorbed when changing from solid to liquid to gas.

Question 19

A person steps out of a hot shower and feels cold, but feels warm again upon returning to the shower area. Which process is responsible for the warming?

Accepted Answer

Condensation of steam on the skin releases energy.

Change of Phase: Physics with Calculus Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards