Outline Chapter 5a Matter and Energy

5-1. Temperature 5-2. Heat 5-3. Metabolic Energy 5-4. Density 5-5. Pressure 5-6. Buoyancy 5-7. Gas Laws

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=(F+40)5/9-40F=(C+40)9/5-4053oC = ?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

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. Density MD = ------- 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

5-5. Pressure FP = ------- 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 PressurePump 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.

Bernoulli’s Principle

The pressure in a moving liquid or gas is less than

the pressure in a stationary liquid or gas.

This explains how airplanes fly.

5-6. 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

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.

Absolute Zero

Absolute zero is -273° C and is the theoretical but unreachable lowest possible temperature.

Outline Chapter 5b Matter and Energy

5-8. Kinetic Theory of Gases5-9. Molecular Motion and Temperature 5-10. Liquids and Solids5-11. Evaporation and Boiling 5-12. Melting 5-13. Heat Engines 5-14. Thermodynamics 5-15. Fate of the Universe 5-16. Entropy

5-8. Kinetic Theory of Gases

A. 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 volume of 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.

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.

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

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. OR The universe is always going toward a state of disorder (entropy is always increasing in the universe).

5-15. Fate of the Universe5-16. 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.

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

42

Dark Energy

In a 1998 study led by Adam Riess, and a group of scientists from the Mount Stromlo Observatory, which is part of the Australian National University, Harvard University and Johns Hopkins University and Space Telescope Science Institute found, by observing supernovas in distant galaxies that the universe is expanding faster and faster. This violates Newton’s second law of motion that says acceleration is due a force. What force?????

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Dark Energy

Basically, dark energy is what they attribute to the accelerated expansion of the universe which means it isn’t dark as to light, but dark as to they know nothing about it. Attempts to explain or measure this energy have largely failed.

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Dark Matter

Dark matter was discovered by observing that the arms of spiral move at the same speed in violation of Kepler’s Law of planetary motion. It was explained by some unknown (dark) matter that distorted known gravitational effects. It was later found that the gravity of super massive black holes at the center of galaxies was not enough to hold the galaxies together. Gravity was not enough to hold the small local clusters of galaxies together as well as the super clusters of galaxies. Long filamental lines of matter, evident of some sort of attractive forces, has also been found between the super clusters of galaxies. Dark Matter has been used to explain all of these

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New Model of the Cosmos

The new model of the Cosmos puts about 4.6% of the

universe being made up of atoms and molecules like what we think we know something about, about 23% is made up by dark matter and the rest (72%) is composed of dark

energy.

They say the Universe was different 13.7 billion years

ago?????