Ch. 23+24 Physics test

Freezing occurs when matter changes from a

liquid to a solid.

Calculate the ideal efficiency of a power plant that runs between temperatures 600 K and 400 K.

(600-400)/600

Ideal Efficiency

(T hot - T cold)/T hot

At what temperature would the molecules of a gas have twice the average kinetic energy they have at a 20°C room temperature?

20+273= 293

One hundred joules of heat is added to a system that performs 60 joules of work. The internal energy change of the system is

40 J.

An ice skater skates on a thin film of water between the blades and the ice.

True

If a volume of air has a temperature of 0 degrees Celsius, an equal volume of air that is twice as hot has a temperature of about 273 degrees C.

True

If air pressure above water is removed, the water will boil and the resulting cooling can turn the water to ice.

True

It is possible to totally convert a given amount of mechanical energy into heat.

True

The process of boiling actually cools the water.

True

The greater the difference in temperature between the input reservoir and output reservoir for a heat engine, the

greater the efficiency.

When water freezes, it

gives off energy

At high altitudes, the boiling point of water

is lower.

Increased air pressure on the surface of hot water tends to

prevent boiling

As a system becomes more disordered, entropy decreases.

False

It is possible to wholly convert a given amount of heat energy into mechanical energy.

False

The lowest temperature possible in nature is 4 K.

False

When ice changes to water at 0 degrees Celsius, energy is released.

False

When steam changes to water at 100 degrees Celsius, energy is released.

False

Clouds form when warm air

chills. expands. rises

The first law of thermodynamics is a restatement of the

conservation of energy.

When a volume of air expands against the environment and no heat enters or leaves, the air temperature will

decrease.

The molecules in a room-temperature glass of water jostle around at

great variety of speeds.

When a volume of air compresses and no heat enters or leaves, the air temperature will

increase.

Suppose you put a closed, sealed can of air on a hot stove burner. The contained air will undergo an increase in

internal energy. temperature. pressure.

Evaporation is a cooling process and condensation is

the more energetic molecules escape the liquid. the temperature of the remaining liquid decreases.