Physics Ch 4

Cooking plans made from which of the following metals would need less heat to achieve a certain cooking temperature?

Copper

Kilocalorie (kcal)

The amount of energy needed to increase the temperature of 1 kilogram of water 1 degree Celsius.

As a solid undergoes a phase change to a liquid, it

absorbs heat while remaining at a constant temperature

The phase change from ice to liquid water takes place at

constant temperature

The transfer of heat that takes place by the movement of groups of molecules with higher kinetic energy is

convection

The transfer of heat that takes places because of density difference in fluids is

convection

A heat engine is designed to

convert heat into mechanical energy

Element

smallest particle which retains the chemical properties of that element.

Conduction best takes place in a

solid

Phases

Solid, liquid, and gaseous

Suppose ammonia is spilled in the back of a large room. If there were no air currents, how would the room temperature influence how fast you would smell ammonia at the opposite side of the room?

Warmer is faster

Phase change

When a solid, liquid, or gas changes from one phase to another. Always absorbs or releases a quantity of heat that is not associated with a temperature change.

The specific heat of copper is 0.093 cal/gC, and the specific heat of aluminum is 0.22 cal/gC. The same amount of energy applied to equal masses, say, 50.0 g of copper and aluminum, will result in

a higher temperature for copper.

Vapor

a substance in a gaseous state that normally exists in the liquid state at room temperature and pressure.

The transfer of heat that takes place directly from molecule to molecule is

conduction

3 facts of the second law of thermodynamics

1) all naturally-occurring processes go in the direction that increases entropy 2) the net effect of all processes raises the total entropy of the universe 3) no engine can be made which converts all absorbed heat into work

2 ways heating can occur:

1) from a temperature difference, with the energy moving from the region of higher temperature 2) from an object gaining energy by way of an energy-form conversion, which includes doing work on it.

4 ways to increase evaporation:

1) raise liquids temp 2) increase the surface area of the liquid 3) remove the vapor just above the liquid's surface 4) by lowering the pressure of the liquid

What is the specific heat of water?

1.0

The temperature known as room temperature is nearest to

20C

Using the Kelvin temperature scale, the freezing point of water is correctly written as

273 K

What is the average speed at room temp?

400 m/sec

Which of the following contains the most heat?

A barrel of water at 0C

Temperature

A measure of the average kinetic energy of the molecules making up the substance.

Heat

A measure of the internal energy that has been absorbed or transferred from one body to another.

The specific heat of copper is roughly three times as great as the specific heat of gold. Which of the following is true for equal masses of copper and gold?

A piece of copper stores three times as much heat at the same temperature.

Entropy

A thermodynamic measure of disorder ( no patterns, randomized, and spread out). The total entropy of the universe continually increases.

Rankin scale

Absolute scale for the English system.

Calorie (cal)

Defined as the amount of energy (or heat) needed to increase the temperature of 1 gram of water 1 degree Celsius. 1 calorie = 4.184 joules.

Specific heat

Defined as the amount of heat needed to increase the temperature of 1 gram of a substance 1 degree Celsius.

Molecule

Defined as the smallest particle of a compound or a gaseous element that can exist and still retain the characteristic properties of that subject.

Which of the following supports the second law of thermodynamics?

Energy tends to degrade, becoming of lower and lower quality.

Fahrenheit scale

Invented by a German physicist in about 1715. Water was used as the standard, with 32F set as the freezing temp and 212F as the boiling temp of water. Associated with the English system of units.

Celsius scale

Invented by a Swedish astronomer. Water was used as the standard, with 0C being freezing temp and 100C as the boiling temp of water. This scale is also known as the Centigrade scale and is associated with the SI unit system.

Radiation

Involves the form of energy called radiant energy, energy that moves through space.

The second law of thermodynamics tells us that the amount of disorder called entropy, is always increasing. Does the growth of a plant or animal violate the second law?

No, the total entropy of the universe increases.

British thermal unit (Btu)

One Btu is the amount of energy (or heat) needed to increase the temperature of 1 pound of water 1 degree Fahrenheit.

What form of heat transfer will warm your body without warming the air in a room?

Radiation

Latent heat of vaporization (Lv)

The heat involved in a liquid-gas phase change where there is evaporation or condensation. For water, the latent heat of vaporization is 540.0 cal/g.

Latent heat of fusion (Lf)

The heat involved in a solid-liquid phase change in melting or freezing. For water the latent heat of fusion is 80.0 cal/g.

Internal energy

The total kinetic and potential energy of the molecules of an object. Represented by "U".

External energy

The total potential and kinetic energy of an everyday-sized object.

Conduction

The transfer of energy from molecule to molecule.

Convection

The transfer of heat by a large-scale displacement of groups of molecules with relatively higher kinetic energy.

Kelvin scale

The zero point is thought to be the lowest limit of temperature. Absolute zero is the lowest temp possible, occurring when all random motion of molecules was historically projected to cease. Absolute zero is written as 0k. -270C = 0K.

Kinetic Molecular Theory

Theory that all matter is made up of tiny, basic units of structure called atoms.

At temperatures above freezing, the evaporation rate can equal the condensation rate only at

any temperature

The temperature of a gas is proportional to the

average kinetic energy of the gas molecules

More molecules are returning to the liquid state than are leaving the liquid state. This process is called

condensation

Cohesion

defined as the attractive force between the same kinds of molecules

Adhesion

defined as the attractive force between unlike molecules

The work that a heat engine is able to accomplish is ideally equivalent to the

difference between the heat supplied and the heat rejected.

The energy supplied to a system in the form of heat, minus the work done by the system, is equal to the change in internal energy. This statement describes the

first law of thermodynamics

Convection best takes place in a (an)

fluid

The heat death of the universe in the future is when the universe is supposed to

freeze at a uniform low temperature

Latent heat is "hidden" because it

goes into or comes out of internal potential energy

The cheese on a hot pizza takes a long time to cool because it

has a high specific heat

Liquids

have a definite volume but no definite shape

Solids

have both a definite volume and a definite shape

Gases

have no definite volume or no definite shape

Anytime a temperature difference occurs, you can expect

heat movement from any higher-temperature region.

Styrofoam is a good insulating material because

it contains many tiny pockets of air

The great cooling effect produced by water evaporating comes from its high

latent heat

The heat involved in the change of phase from solid ice to liquid water is called

latent heat of fusion

Which of the following has the greatest value for liquid water?

latent heat of vaporization

When you add heat to a substance, its temperature

might stay the same

The Fahrenheit thermometer scale is

no more accurate than the Celsius scale.

The transfer of heat that takes place by energy moving through space is

radiation

Fluids

refer to both liquids and gases, because they both can "flow".

Plasma

refers to an "ionized state" of matter. When atoms of matter in the gaseous state have their outer electrons removed such that they become "charged particles".

The space above the liquid's surface is said to be

saturated (100% humidity)

If you want to move heat from a region of cooler temperature to a region of warmer temperature, you must supply energy. This is described by the

second law of thermodynamics

The second law of thermodynamics

states that heat flows from objects with a higher temperature to objects with a cooler temperature.

The first law of thermodynamics

states that the energy supplied to a thermodynamic system in the form of heat, minus the work done by the system, is equal to the change in internal energy.

On the Celsius temperature scale

the numbers relate to the boiling and freezing of water

The specific heat of soil is 0.20 kcal/kgC, and the specific heat of water is 1.00 kcal/kgC. This means that if 1 kg of soil and 1 kg of water each receives 1 kcal of energy, ideally

the soil will be 4C warmer than the water.

Heat is the

total internal energy of an object.

External energy refers

total potential energy and kinetic energy of an object that you can measure directly.

Internal energy refers to

total potential energy and kinetic energy of the molecules.

Radiation is the only method of heat transfer that can take place in a

vacuum

The evaporation of water cools the surroundings, and the condensation of this vapor

warms the surroundings