Physical Science Chapter 6

Which of the following changes would make the water balloon more likely to pop? (Ignore effects of convection within the fluid.)

1. Use a thicker balloon. 2. Use a liquid that has a lower heat capacity than water.

What is the temperature for boiling water on the Celsius scale?

100 C

Find the amount of heat that is required to warm 105 kg of water for you bath by 30 ∘C.

105*30*4.184= 13.2 J

What is the temperature for freezing water on the Fahrenheit scale?

32 F

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

FALSE

Which of the following would best describe the conductive properties of wood?

It is a good insulator.

What happens to the conductive properties of wood when it gets very hot?

It will continue to remain a good insulator.

What is the definition of temperature?

Measure of the average translational kinetic energy per particle of an object.

What happens to the thermal energy of a system when mechanical work is done on the system?

Thermal energy increases.

What is the definition of heat?

Thermal energy transferred from one object to another due to a temperature difference.

How would you walk on red-hot coals without getting your feet burned?

Walk fast

If air were a better conductor than it is, at nighttime the earth would be

considerably colder.

If a volume of air is warmed, it expands. If a volume of air expands, it

cools

When a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. The reason for this is

copper expands more than iron.

When work is done by a system and no heat added to it, the temperature of the system

decreases

When water at 4°C is heated it expands. When water at 4°C is cooled, it

expands

Thermal convection applies mainly to

fluids

When you touch a cold piece of ice with your finger, energy flows

from your finger to the ice.

Which of the following expands most when the temperature is increased? Equal volumes of

helium.

Some molecules are able to absorb large amounts of energy in the form of internal vibrations and rotations. Materials composed of such molecules have

high specific heat capacities.

Compared to a giant iceberg, a hot cup of coffee has

higher temperature, but less thermal energy.

An object will normally be a net radiator of energy when its temperature is

higher than it surroundings

Which of the following contracts most when the temperature is increased? Equal volumes of

ice water

Suppose you rapidly stir some raw eggs with an eggbeater. The temperature of the eggs will

increase

Your feet feel warmer on a rug than on a tile floor because the rug

is a better insulator than tile.

Ice has a lower density than water because ice

is made of open-structured, hexagonal crystals.

Heat energy is measured in units of

joules and calories

If you stake out a plot of land with a steel tape on a very hot day, the amount of land you will have will be

larger

When an iron ring is heated, the hole becomes

larger

Place a 1-kg block of iron at 40°C into a kilogram of water at 20°C and the final temperature of the two becomes

less than 30°C.

If a poor absorber of radiation were a good emitter, its temperature would be

less than its surroundings

Which generally expands more for an equal increase in temperature − solid or liquid?

liquid

A substance that heats up relatively quickly has a

low specific heat capacity.

One of the main reasons people can walk barefoot on red-hot coals of wood without burning their feet has to do with

low thermal conductivity of the coals.

Suppose that we replace the aluminum with a mystery metal and repeat the experiment in the video. As in the video, the mass of the metal is the same as that of the water. Room temperature is about 20∘C before the start of the experiment. The water heats up to 40∘C, and the mystery metal heats up to 80∘C. Compared to that of water, the heat capacity of our mystery metal is...

one-third as great.

A good reflector of radiation is a

poor absorber of radiation.

Warm air rises because faster moving molecules tend to move to regions of less

pressure and density

Consider a closed, sealed can of air placed on a hot stove. The contained air undergoes an increase in

pressure and temperature

The planet Earth loses heat mainly by

radiation

What exactly is radiant energy?

Energy of electromagnetic waves.

On a chilly 10°C day, your friend who likes cold weather wishes it were twice as cold. Taken literally, this temperature would be

-131.5°C.

The lowest temperature possible in nature is

-273°C. OR 0 K

What is the temperature for freezing water on the Celsius scale?

0 C

How much energy can be taken from a system at a temperature of 0 K?

0 J

What is the relationship between calories and joules?

1 cal = 4.19 J

What is the temperature for boiling water on the Fahrenheit scale?

212 F

A volume of air has a temperature of 0°C. An equal volume of air that is twice as hot has a temperature of

273°C

Consider a piece of metal that is at 5°C. If it is heated until it has twice the thermal energy, its temperature will be

283°C.

Consider a piece of metal that is at 10°C. If it is heated until it has twice the thermal energy, its temperature will be

293°C.

Pounding a nail into wood makes the nail warmer. Consider a 7-g steel nail 6 cm long and a hammer that exerts an average force of 540 N on the nail when it is being driven into a piece of wood. Find the change in the nail's temperature after it was pounded into the piece of wood completely. (Assume that the specific heat capacity of steel is 450 J/kg⋅∘C.)

540*.06= 32.4 450*.007= 3.15 32.4/ 3.15= 10.3∘C

From best to worst, rank these materials as heat conductors: (a) copper wire, (b) snow, and a (c) glass rod.

A- copper wire (best) C- glass rod B- snow (worst)

What is the definition of a calorie?

Amount of heat needed to change the temperature of 1 gram of water by 1 degree Celsius.

What is the definition of a Calorie?

Amount of heat needed to change the temperature of 1 kilogram of water by 1 degree Celsius.

Rank the magnitudes of these units of thermal energy from greatest to least: (a) 1 calorie, (b) 1 Calorie, (c) 1 joule.

B- Calorie A- calorie C- joule

From greatest to least, rank the frequency of radiation of these emitters of radiant energy: (a) red-hot star, (b) bluehot star, and (c) the Sun.

B- blue-hot star C- the Sun A- red-hot star

Rank from greatest to least the volume of water at these temperatures: (a) 0°C, (b) 4°C, and (c) 10°C.

C-10, A-0, B-4

An object will normally be a net radiator of energy when its thermal energy is

Can't say, because thermal energy is not temperature.

Why does the direction of coastal winds change from day to night?

During the day the shore is warmed more than the water, so winds blow from water toward shore. At night the shore cools more than the water, and winds blow in the opposite direction.

What is heat radiation?

Electromagnetic radiation in the infra-red part of the spectrum.

Distinguish between a heat conductor and a heat insulator.

Electrons are free to migrate in conductors, therefore, they conduct heat easily. Electrons are firmly attached in insulators, therefore, they don't conduct heat well.

Why does a penny become warmer when it is struck by a hammer?

Striking makes atoms in the metal move faster.

What determines the direction of heat flow?

Temperature difference determines the direction of heat flow. The heat flows from the object with high temperature to the object with low temperature.

Is the temperature of an object a measure of the total translational kinetic energy of the molecules in the object or a measure of the average translational kinetic energy per molecule in the object?

Temperature is a measure of the average translational kinetic energy per molecule in the object.

Why is one able to walk on red-hot coals without getting one's feet burned?

The coals are not good conductors of heat.

When you touch a cold surface, does cold travel from the surface to your hand or does energy travel from your hand to the cold surface?

The energy travels from the hand to the surface.

How does the frequency of radiant energy relate to the absolute temperature of the radiating source?

The frequency of radiant energy is directly proportional to the absolute temperature of the source.

Describe how convection transfers heat.

The heat is transferred by means of currents in the heated fluid or gas.

How does the second law of thermodynamics relate to the direction of heat flow?

The second law of thermodynamics defines the direction of the spontaneous heat flow − from a higher-temperature substance to a lower-temperature substance.

How does the specific heat capacity of water compare with the specific heat capacities of other common materials?

The specific heat capacity of water is very high in comparison with other common materials.

Does a substance that heats up quickly have a high or low specific heat capacity?

The substance that heats up quickly has a low specific heat capacity.

What happens to the temperature of air when it expands?

The temperature decreases.

What happens to the temperature of the system?

The temperature increases.

What is the definition of a joule?

Work done in applying a force of one newton through a distance of one meter.

If you are able to grab a hot pan and pull it out by the handle without burning yourself, what kind of handle must the pan have, and why?

a wooden handle, because it is the better insulator

Consider a metal ring with a gap cut in it. When the ring is heated, the gap

becomes wider

Hot water will cool to room temperature faster in a

black pot

Thermal energy, the energy internal to a substance, is composed mainly of

rotational, vibrational, and translational motions of particles.

Entropy is closely related to the

second law of thermodynamics.

The higher the temperature of an object, the

shorter the wavelengths it radiates.

Which warms up faster when heat is applied − iron, silver, or water?

silver

Ice tends to form at the

surface of bodies of water.

If an object radiates more energy than it absorbs, its

temperature decreases. thermal energy decreases

Heat energy travels from an object with a high

temperature to an object with a lower temperature.

The reason that the white-hot sparks that strike your skin from a 4th-of-July-type sparkler don't harm you is because

the energy per molecule is high, but the total energy transferred is small.

The fact that a thermometer "takes its own temperature" illustrates

thermal equilibrium.

What kinds of particle motion account for thermal energy?

translational, rotational, vibrational

When ice floats in water, a small part of it extends above the surface. Interestingly enough, the volume of ice that extends above the surface is equal to the volume of the

vast number of open spaces in the hexagonal ice crystals.