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)5/9-40
F=(C+40)9/5-40
127.4oF
53oC = ?oF
35oC
95oF = ?oC
Measuring Temperature
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.
Expansion
of a liquid
Measuring Temperature
Expansion of a liquid
Bakersfield College
Physical Science PHSC-B11
James Prescott Joule
(1818-1889)
5-2. Heat
 British Brewer
Conducted an experiment to conclusively
James
Prescott
The SI unit of heatsettle
is the joule
as wellover
as the
calorie.
Joule
the debate
heat
as a form of
(1818-1889)
energy
Heat can be transferred in three ways:
1. Conduction,
whichthe
heat is transferred from one place to
Joule
developed
Joulein
developed
the
law
of
lawmolecular
of conservation
conservation
another by
collisions.
of
of energy
energy when
when he
he
2. Convection,
in As
which
heat is carried by the motion of a
was
aa result
was 29.
29.
As
result
of his
his work,
work, the
the SI
SI
volume ofof
hot
fluid.
units
units for
for work
work (J)
(J)
were
named
for
him
named for
him is transferred by electromagnetic
3. Radiation,were
in which
heat
waves.
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
Water
Human Body
Concrete
Alcohol (ethyl)
Ice
Steam
Wood
Aluminum
Glass
Iron
Copper
Gold
Specific Heat kJ/kg Co
4.2
3.5
2.9
2.4
2.1
2.0
1.8
0.92
0.84
0.46
0.39
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
kcal
1 raw onion
5
1 dill pickle
15
1 gum drop
35
1 poached egg
75
1 banana
120
1 cupcake
130
1 broiled hamburger patty 150
1 glass of milk
165
1 cup bean soup
190
1 cup tuna salad
220
1 ice cream soda
325
½ broiled chicken
350
1 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
M
D = ------V
Find the mass of water in
the bathtub above.
M
1000kg
D == ------M
D V = ----------- (0.234 m3) = 234kg
V
1 m3
or 1 g/cm3
5-5. Pressure
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.
F
P = ------A
5-5. Pressure
Pressure exerted by 60kg woman’s heel onto
the floor is about 40
times the estimated
pressure of the feet of a
35-ton apatosaurus on
the ground.
P = F/A = 588N/5x10-5m2 = 1.2x107N/m2 = 12 MPa
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 enginedriven 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
Fb= dxVxg
P=ρxgxdepth
Archimedes' principle states: Buoyant force on
an object in a fluid is equal to the weight of fluid
displaced by the object.
5-6. Buoyancy
Fb= dxVxg
P=ρxgxdepth
Weighing by Volume
You 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.
Item
Mass
Volume
Wood 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
5-6. Buoyancy
Fb= dxVxg
P=ρxgxdepth
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.
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
Boyle’s Law
P1
P2
=
Charles’s Law
V2
V1
V1
T1
=
Ideal Gas Law
V2
P1V1
T2
T1
=
P2V2
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 Gases
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
5-8. 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
FB
These
canthe
only
formofwhen
the the
gas
• As
heated,
bubbles
gas begin
to
Asliquid
thebubbles
gasis inside
bubbles
expands,
inside
has enough
to overcome
form
buoyant
force pressure
on
the bubble
grows, the
pressure in
the liquid
atmosphere
eventually
causing
it to and
rise to
the surface
above the liquid
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 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.
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
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?????
42
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.
43
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
44
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?????
45