Ch4 Flashcards
description of what happens after the gasoline/air vapor mixture ignites
The gasoline/air vapor _ within the piston chamber, causing it to do _
description of what happens after the gasoline/air vapor mixture ignites
The gasoline/air vapor expands within the piston chamber, causing it to do work
why sun warms us up
During heat radiation, the object absorbs more radiation than it emits, allowing the object to get hotter and hotter
efficiency eqt
hot-cold/hot
In a heat engine, the energy from the so-called “hot reservoir” goes where?
Into the cold reservoir and into doing work.
describes what the temperature of an object measures?
The average thermal energy per particle making up the object.
In the process of convection, once a particle has been warmed up:
it cycles through the _, losing _ but eventually _ to the _and warming up once again.
In the process of convection, once a particle has been warmed up:
it cycles through the system, losing energy but eventually returning to the heat island and warming up once again.
describe Heat death of the universe
The idea that all energy in the universe will ultimately wind up as unusable energy
A heat engine produces work by which of the following?
Heat is converted to _ and the _ is expelled.
A heat engine produces work by which of the following?
Heat is converted to work and the excess heat is expelled.
Natures direction
Tendency of all systems to evolve from _ to more _ states
Tendency of all systems to evolve from improbable to more probable states
heat is
_ in motion
heat is energy in motion
Two objects are defined to be at the same temperature if _
Two objects are defined to be at the same temperature if no net heat flows spontaneously from one to the other
Gallon vs pint of water
Same heat?
Same temp?
Gallon has more heat (internal energy) than a pint, but they are at the same temperature
Difference
Heat is form of energy, temperature is a measurement
Temp Scales
water freeze and boil
F
C
K
Fahrenheit
0: Mixture of ice, salt, and water
32: ice melt
96: human body temp (real 98)
Celsius
0: water freezing
100: water boiling
Kelvin
0: absolute zero= motion stops
1k=1c
273=water freeze
373=water boil
what is absolute zero
Absolute zero= 0K
Impossible to extract heat from atoms (stop moving)
Factors determine how quickly heat is transferred between objects
Temperature difference
Thermal conductivity
Distance
Is it more energy efficient to keep at constant temperature or set it on a variable schedule
If you keep it on constant you will lose more energy when it is too cold or at night when there is a large temperature difference
Specific heat capacity
a measure of the ability of a material to _ and is defined as the _ required to raise the temperature of one gram of that material by 1°C
largest heat capacity?
Specific heat capacity
a measure of the ability of a material to absorb heat and is defined as the quantity of heat required to raise the temperature of one gram of that material by 1°C
large heat capacity?= water
Conduction
The movement of heat by _ atoms or molecules
A chain of collisions occurs, with atoms progressively farther and farther away from the heat source moving_
Conduction
The movement of heat by collisions between vibrating atoms or molecules
A chain of collisions occurs, with atoms progressively farther and farther away from the heat source moving faster and faster as time goes by
Why does insulation work?
Thermal _ differences
The ability of a material to transfer _ from one molecule to the next by _
Thermal conductivity differences
The ability of a material to transfer heat energy from one molecule to the next by conduction
Heat conductor vs heat insulator
Insulator= low thermal conductivity
Convection
The transfer of heat by the _ of fluid or air.
Dense, cooler fluids (liquids and gases) _ bulk and _, which are less dense
Convection
The transfer of heat by the physical motion of masses of fluid or air.
Dense, cooler fluids (liquids and gases) descend in bulk and displace rising warmer fluids, which are less dense
How do cities create their own weather
Cities help create their own weather because they are heat islands where convection cells develop.
Rainfall is typically higher in cities than in the surrounding atmosphere because cities set up convection cells that draw in cool moist air from surrounding areas.
Why fiber glass good insulator
composition
how it disrupts 2 heat transfers
loosely intertwined strands of glass. It works by minimizing the opportunities for conduction and convection of heat out of your home.
it takes a long time for heat to move along a thin, twisted glass fiber, and even longer for heat to transfer across the occasional contact points between pairs of crossed fibers.
Furthermore, a cloth-like mat of fiberglass disrupts airflow and prevents heat transfer by convection.
describe thermocline and upwelling
Thermocline
- Transition layer between warm surface water and cold deep water
Upwelling
- Wind push water away
- Nutrient rich water from below takes it’s place
- Fertilize ocean surface
- Good fishing when this occurs
Describe ENSO (SA and AUS)
Normal year
El nino year
Normal yearTrade winds go from SA to AUS.
- Upwelling in SA
- Trade winds Push water towards AUS
- Water warmer in AUS
- Convection cell- heat rises in AUS
El Nino= warm phase
- Higher air pressure in AUS bring opposing winds
- Trade winds decrease in strength
- Normal flow of water away from SA decreases and piles up of SA
- Pushes thermocline deeper and decreases upwelling
- Deeper thermocline and decreased water trasport from SA to AUS, the sea surface increases greater than normal around SA
Radiation
Transfer of heat by_- wave energy
When bodies at EQ with environment?
Radiation
Transfer of heat by electromagnetic radiation- wave energy
EQ= no loss of energy if object at same temperature as surroundings
How does body control temperature?
heat transfer
- Body temp up
- blood vessels near the surface of your skin dilate so that the blood can carry more heat to the surface by convection.
- excess heat can be radiated away and conduction happens.
- In addition, you start to sweat. The purpose of sweating is to put water on your skin, which then evaporates through your body heat.
The second law of thermodynamics places restrictions on the way _ can be transferred and used to do _
Statements
- Heat will not flow _ from a _ to a _ body (ON ITS OWN)
- You cant make an engine that does nothing but_
- Every isolated system becomes more _ with time (HIGH _)
The second law of thermodynamics
places restrictions on the way heat and other forms of energy can be transferred and used to do work
Statements
- Heat will not flow spontaneously from a cold to a hot body (ON ITS OWN)
- You cant make an engine that does nothing but convert heat to useful work
- Every isolated system becomes more disorder with time (HIGH ENTROPY)
Heat will not flow spontaneously from a cold to a hot body
- Explain
- How could be violated
If two objects collide and one of them is moving faster than the other, chances are that the slower object will be speeded up and the faster object slowed down by the collision. It’s unlikely that events will go the other way. Thus, as we saw in the discussion of heat conduction, faster-moving molecules tend to share their energy with slower-moving ones.
On the macroscopic scale, this process is seen as heat flowing from warm regions to cold ones by conduction. For the second law to be violated, the molecules in a substance would have to conspire so that collisions would cause slower-moving molecules to slow down even more, giving up their energy to faster molecules so they could go even faster.
You cant make an engine that does nothing but convert heat to useful work
This second statement of the second law tells us that whenever energy is _, some of the _ must be dumped into the environment and is unable to do _
This second statement of the second law tells us that whenever energy is transformed from heat to another type, some of the heat must be dumped into the environment and is unable to do work
Efficiency
Quantifies loss of _
Efficiency
Quantifies loss of useful energy
How an engine works
Exploding mixture of _ creates a _ gas that pushes down on a piston.
The piston’s motion is converted into _ of a series of machine parts that eventually _.
Some of the energy is lost because of _, but the second law of thermodynamics predicts that our use of the energy is restricted even if _
How an engine worksIgnition
Exploding mixture of gasoline and air creates a high-temperature, high-pressure gas that pushes down on a piston.
The piston’s motion is converted into rotational motion of a series of machine parts that eventually turn the car’s wheels.
Some of the energy is lost because of friction, but the second law of thermodynamics predicts that our use of the energy is restricted even if friction did not exist
The second law of thermodynamics says that any engine operating between _ must dump some energy in the form of _ into the _
The second law of thermodynamics says that any engine operating between two temperatures must dump some energy in the form of heat into the low-temperature reservoir
why petroleum reserves and coal deposits play such an important role in the world economy
Can produce _
Can be used _
Large portion of energy is _ when combusted as heat
why petroleum reserves and coal deposits play such an important role in the world economy
Can produce high temp res
Can be used once
Large portion of energy is wasted when combusted as heat
Why use fossil fuels for heating?
how much energy water when used for electricity generation?
- no engine envolved so not much heat loss in process
- MORE THAN 2/3 of the energy WASTED as heat
- Electricity you have to convert fossil fuel to electricity then heat up
highly ordered configurations are _ because almost every possible configuration is _
An _ system is one in which a number of objects, be they atoms or automobiles, are positioned in a completely regular and predictable pattern
A _ system, on the other hand, contains objects that are randomly situated, without any obvious pattern.
highly ordered configurations are improbable because almost every possible configuration is disordered
An ordered system is one in which a number of objects, be they atoms or automobiles, are positioned in a completely regular and predictable pattern
A disordered system, on the other hand, contains objects that are randomly situated, without any obvious pattern.
According to the second law of thermodynamics, any system left to itself will evolve toward the_, the state with the maximum _ in the arrangement of its parts.
According to the second law of thermodynamics, any system left to itself will evolve toward the most disordered state, the state with the maximum uncertainty in the arrangement of its parts.
Why does refrigerator not violate 2nd law of thermo
Not isolated due to power cord- power station
Systems total entropy must increase
Ice cube- entropy decrease
Power plant- burning fuel and surrounding air become more disordered
All that the second law requires is that the increase of disorder at the generating plant be greater than the increase of order at the ice cube. As long as this requirement is met, the second law is not violated
describe heat death of universe
2nd law- all energy will eventually degrade into waste heat= maximum state of entropy
All waste heat= all bodies come to same temperature= no heat transfer between two bodies= since no heat flow, no work can be aquired by heat transfer. No just thermal heat, but all forms. Since no more work can be extracted, the universe is said to be dead
Difference between motion laws and thermo laws
The arrow of time
Dimensions of space have no direction
The motions predicted by Newton and the conservation of energy are independent of time.*
The second law of thermodynamics is different. By defining a sequence of events, we have established a direction to time
Does evolution violate 2nd law?
The energy that drives living systems is sunlight, so that the “isolated system” that the second law speaks of is Earth’s biosphere plus the Sun.
evolution of life consistent with the second law is that the order observed in living things must be offset by a greater amount of disorder in the Sun
Does the First Law of Thermodynamics imply a directionality in nature?
ICE melting
Yes-Move from improbable state to probable state
BUT from perspective of energy conservation
KE Air
higher temp
- Fast molecules collide with slower ice mols
- Temp of ice = melt and eventually room temp
- BUT highly improbable Water mol donate energy to mol of the air and get converted into ice again
- Very improbable
What is specific heat capacity? Which heats more quickly, a kilogram of water or a kilogram of copper?
SHC
Ability of material to absorb heat
High SHC= more heat needed to raise temp
Amount of heat needed to increase temp by 1 degree C
How did Daniel Fahrenheit produce the temperature scale that bears his name?
All values to be positive
Coldest temperature he could create in lab as 0
Ice, water, salt
Human body temperature of 96
What makes a good conductor of heat? What makes a good insulator?
Heat transferred by vibration of atoms= collide to cause other to vibrate faster= transfer of heat
Good conductor
Atoms in lattice are vibrate/ move in lattice
Good insulator
Atoms tightly bound to lattice so don’t vibrate much= bad conductor
Explain why heat only flows spontaneously from hot to cold objects.
2nd law says it cant happen on its own accord- have to supply energy
- conservation of energy KE
If two objects collide and one of them is moving faster than the other, chances are that the slower object will be speeded up and the faster object slowed down by the collision. It’s unlikely that events will go the other way. Thus, as we saw in the discussion of heat conduction, faster-moving molecules tend to share their energy with slower-moving ones.
State the second law of thermodynamics in three different ways. In what ways are these three statements equivalent?
Heat will not flow spontaneously from cold to hot body
You cannot construct and engine that does nothing but convert heat to useful work
Every isolated system becomes more disordered with time
LINK
They all predict the direction in which a system will drive if left to do so on its own
In what way is aging an example of the second law of thermodynamics?
Aging= evolving towards disordered state
Disorder= immune system weak/ body parts are not able to function as well as they used to
