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Outline Chapter 5 Matter and

Energy

5-9. Molecular Motion and

Temperature

5-10. Liquids and Solids

5-11. Evaporation and Boiling

5-12. Melting

5-13. Heat Engines

5-14. Thermodynamics

5-15. Fate of the Universe

5-16. Entropy

5-1. Temperature

5-2. Heat

5-3. Metabolic Energy

5-4. Density

5-5. Pressure

5-6. Buoyancy

5-7. Gas Laws

5-8. Kinetic Theory of

Gases

5-1. Temperature

Temperature = average kinetic energy.

Heat= total energy.

The Lake and the glass of water both are at

70oF. Which has the most heat?

5-1. Temperature

5-1. Temperature

The fahrenheit scale in which water freezes at 32°F and boils at 212°F at sea level.The celsius scale in which water freezes at 0°C and boils at 100°C at sea level.

C= 5/9 (oF - 32)F= 9/5 (oC) + 3253oC = ?oF95oF = ?oC

127.4oF35oC

Measuring Temperature

Expansion of a liquid

Difference in expansion of two

metals side by side

A thermostat makes use of the different rates of thermal expansion in the metals of a

bimetallic strip to switch heating and cooling systems on and off.

Measuring Temperature

Expansion of a liquid

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5-2. Heat

The SI unit of heat is the joule as well as the calorie.

Heat can be transferred in three ways:

1. Conduction, in which heat is transferred from one place to another by molecular collisions.

2. Convection, in which heat is carried by the motion of a

volume of hot fluid.3. Radiation, in which heat is transferred by electromagnetic

waves.

James Prescott

Joule

(1818-1889)

5-2. Heat

The heat needed to change the temperature of 1 kg of a substance by 1° C is different for different substances.

5-2. Heat

Specific Heat is a measure of how much heat a substance can hold. Water holds more heat per gram than any other substance.

Substance Specific Heat kJ/kg Co

Water 4.2Human Body 3.5Concrete 2.9Alcohol (ethyl) 2.4Ice 2.1Steam 2.0Wood 1.8Aluminum 0.92Glass 0.84Iron 0.46Copper 0.39Gold 0.13

5-3. Metabolic Energy

The complex of biochemical reactions that make food energy

available for use by living organisms is called metabolism.A kilocalorie (4.2kj) is the amount of heat needed to change the

temperature of 1 kg of water by 1° C; it is equal to one dietary

"calorie."

Food kcal1 raw onion 51 dill pickle 151 gum drop 351 poached egg 751 banana 1201 cupcake 1301 broiled hamburger patty 1501 glass of milk 1651 cup bean soup 1901 cup tuna salad 2201 ice cream soda 325½ broiled chicken 3501 lamb chop 420

5-3. Metabolic Energy

The conversion of metabolic energy into biological work is relatively

inefficient; much of the energy is lost as heat. The maximum metabolic rate or power output depends on the animal’s ability to

dissipate heat.

5.2 W/kg 1.2 W/kg 0.67 W/kg

5-4. DensityM

D = -------V

Find the mass of water in the bathtub above.

MD = -------

V

1000kg= ----------- (0.234 m3)

1 m3

or 1 g/cm3

M = D V = 234kg

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5-5. PressureF

P = -------A

The SI unit of force is the pascal:

1 pascal = 1 Pa = 1 newton/meter2

Atmospheric pressure at sea level

averages 101 kPa (equals

approximately 15 lb/in2).

Instruments called barometers

measure atmospheric pressures.

5-5. Pressure

P = F/A = 588N/5x10-5m2 = 1.2x107N/m2 = 12 MPa

Pressure exerted by 60-

kg woman’s heel onto the floor is about 40

times the estimated

pressure of the feet of a 35-ton apatosaurus on

the ground.

5-5. Pressure

Measuring Blood Pressure

Pump until blood flow stops. Release until hear

gurgling of blood flow

(systolic). Release until gurgling stops (diastolic).

Normal is 120/80 torr.

Fig. 5.16

Hydraulic ram converts pressure in a liquid into an

applied force. The pressure is provided by an engine-

driven pump.

6-6. Buoyancy

Archimedes' principle states: Buoyant force on

an object in a fluid is equal to the weight of fluid displaced by the object.

Fb= dxVxg

P=ρxgxdepth

5-6. Buoyancy

Item Mass VolumeWood Animal 19.343g 297-277=20 ml

Golf Ball 45.450g 296-250=46 ml

Syringe 2.601g 211-209=2 ml

Ping Pong Ball 3.444g 217-215=2 ml(only a portion is submerged)

Orange Spigot 15.859g 219-204=15 ml

Weighing by VolumeYou can estimate mass by measuring the volume of water an object displaces. Compare the mls the object displaces in a

graduated cylinder below to the measured mass on a balance.

Fb= dxVxg

P=ρxgxdepth

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5-6. Buoyancy

Diet sodas contain no sugar and mostly water. Therefore they displace the same amount of water as in the can and they will barely float.

Non-diet sodas contain sugar which gives them a density greater than water and they will sink.

Fb= dxVxg

P=ρxgxdepth

Fig. 5.18

Air at high pressure in a the tank of a scuba diver is

reduced by a regulator valve to the pressure at the depth of the water. The diver must wear lead weight to overcome his

or her buoyancy. The deeper the diver goes, the greater the

water pressure, and the faster the air in the tank is used up.

Fig. 5.20

Because water expands when it freezes it becomes less

dense and floats. 90% of this ice berg off of Greenland is under water.

5-7. Gas Laws

P1 V2 =

P2 V1

Boyle’s Law

V1 V2 =

T1 T2

Charles’s Law Ideal Gas Law

P1V1 P2V2 =

T1 T2

Fig. 5.38

Pressure Cooker. By increasing

temperature you can

increase the pressure.

Fig. 5.33

The snow making machine shoots expanded mixture of ice and air to freeze to snow.

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Absolute Zero

Absolute zero is -273° C and is

the theoretical but unreachable lowest possible temperature.

5-8. Kinetic Theory of

GasesA. Gas molecules are small compared with the

average distance between them; a gas is mostly empty space.

1. Gases are easily compressed.2. Gases are easily mixed.

3. The mass of a certain volume of gas is much

smaller than that of the same volumeof a liquid or a solid.

B. Gas molecules collide without loss of kinetic energy.

C. Gas molecules exert almost no forces on one another, except when they collide.

http://intro.chem.okstate.edu/1314f00/laboratory/glp.htm

5-10. Liquids and Solids

The intermolecular attractions

between the molecules of a liquid are stronger than those in a gas but

weaker than those in a solid.

Molecules of a solid do not move freely about but vibrate around fixed

positions.

5-9. Molecular Motion and

Temperature•The absolute temperature of a gas is

proportional to the average kinetic energy of its molecules.

•Gas molecules, even at 0 K (-273° C),

would still possess a small amount of kinetic

energy.

•Compression of a gas increases its

temperature; expansion decreases its

temperature.

•Gas molecules are in constant motion

because their collisions result in no net loss of energy.

Increases decreases

5-11. Evaporation and Boiling

Boiling is when vapor pressure equals atmospheric pressure.

Sublimation is the direct conversion of a substance from the solid to the vapor state, or from the vapor state to the solid state, without it entering the liquid state.

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5-11. Evaporation and Boiling

• As liquid is heated, bubbles of gas begin to form

These bubbles can only form when the gas

inside has enough pressure to overcome the

pressure in the liquid and atmosphere

above the liquid

As the gas inside the bubbles expands, the

buoyant force on the bubble grows,

eventually causing it to rise to the surface

FB

Changes of State

heat of vaporization

heat of fusion

Changes of State

5-13. Heat Engines

5-13. Heat Engines

http://auto.howstuffworks.com/engine1.htm

How a Refrigerator Works

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5-14. Thermodynamics

•Thermodynamics is the science of heat transformation.

•The first law of thermodynamics states: Energy cannot be created or destroyed, but it can be converted from one form to another.

•The second law of thermodynamics states: It is impossible to take heat from a source and change all of it to mechanical energy or work; some heat must be wasted.

Heat Engine Efficiency

Maximum efficiency of a heat engine depends on the

temperatures at which it takes in and ejects heat; the greater the ratio between the two temperatures, the more efficient the

engine:

Tcold 368oK Efficiency = 1 - ----- = 1 - -------- = 0.56

Thot 843oK

Steam Engine and Electric Power

Plants

5-15. Fate of the Universe

5-16. Entropy

Entropy is disorder. The universe is increasing its disorder (another version of the 2nd law of thermodynamics).

The heat death of the universe will occur when all particles of matter ultimately have the same average kinetic energy and exist in a state of maximum disorder.

Lecture Quiz 5

1. What do heat engines need to work?

2. What is the difference between heat and temperature?

3. What is room temperature in Centigrade?

4. What are the equations for density and pressure?

5. What is Entropy?

http://jersey.uoregon.edu/vlab/Cannon/

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Lecture Quiz 5

1. What do heat engines need to work? Hot and cold reservoir

2. What is the difference between heat and temperature? T=average KE, H=total energy

3. What is room temperature in Centigrade? 20oC

4. What are the equations for density and pressure? D=M/V P=F/A

5. What is Entropy? Disorder

Lecture Quiz 5

1. What do heat engines need to work?

2. What happens to the temperature of a material while it is melting?

3. What is the maximum efficiency of an engine when the temperature of the fluid in the radiator is 375K and the temperature of the exhaust gases is 750K?

4. What are the two laws of thermodynamics?

5. What is Entropy?

Lecture Quiz 5

1. What do heat engines need to work?Hot and cold reservoir

2. What happens to the temperature of a material while it is melting?It stays the same. Energy goes into phase change.

3. What is the maximum efficiency of an engine when the temperature of the fluid in the radiator is 375K and the temperature of the exhaust gases is 750K?Efficiency = 1- Tcold/Thot = 1-(375K/750k) = 0.50 = 50%

Lecture Quiz 5

4. What are the two laws of thermodynamics?1-Energy cannot be created or destroyed, but it can be

converted from one form to another.

2-It is impossible to take heat from a source and change all of

it to mechanical energy or work; some heat must be wasted or

Entropy is increasing in the universe.

5. What is Entropy?The measure of disorder.