Integrated Physics and Chemistry
Newly designed home refrigerators use _____ as a refrigerant.
# 11 from Quiz 2
The specific heat capacity of silver is 0.06 cal/g°C. How much energy is needed to flow into a 5-gram sample to change its temperature from 10°C to 11°C?
0.3 cal
Second Law of Thermodynamics
1) The tendency of the universe is to increase entropy and decrease the amount of usable energy. 2) Heat will never flow spontaneously from a cold object to a hot object.
How many calories are absorbed by a sample of water with a mass of 500 grams as it changes from 50°C to 56°C? The specific heat capacity of water is 1.00 cal/°C.
3,000 calories
The element in a thermostat that is sensitive to temperature changes is ______________.
A bimetallic strip
Entropy
A measure of disorder.
Why is thermal energy produced not generally usable to do work?
Because ...
A _________ heats water for water-based radiant heat.
Boiler and solar collector
An example of the earliest use of the internal combustion engine is in the _____.
Cannon
Why do heat engines all involve combustion?
Combustion unlocks a huge amount of energy trapped in carbon-hydrogen bonds. Combustion does not require any activation energy to react., Combustion is highly efficient at converting internal energy into mechanical energy., Combustion has a fuel source that is very sustainable., When fuel is combusted it has the ability to convert into mechanical energy to do work, like move a piston.
What heating systems involve circulation of the air in a room?
Convection
First Law of Thermodynamics
Energy cannot be created or destroyed; however, when heat is added to a system, energy can be changed from one form to another.
Exhaust Stroke
Expels waste gases from the cylinder.
The thermodynamic law that explains the movement of heat energy during the refrigeration cycle is the ______ .
First
Gases, fluids, and other solids in contact with a moving object will produce ____ due to friction.
Heat flow
Two rooms are in contact. One is at 15°C and the other at 21°C. Choose the best statement concerning the heat flow.
Heat will flow from the 21°C room to the 15°C room.
A catalytic combustor _______________ on the efficiency of a fireplace.
Increases
A ________ fireplace continues to radiate heat even after the fire is extinguished.
Masonry.
Metals are really good thermal conductors for which of the following reasons?
Metals can absorb more heat flow than other elements before damage occurs. Particles of metallic structure begin to vibrate faster as they absorb energy. Metals have a larger number of freely moving electrons. Metals have high densities. Metals have high melting points.
Zeroth Law of Thermodynamics
Objects in thermal equilibrium have the same temperature, so no heat flows between them.
Internal energy changes that do not register on a thermometer are due to changes in the_________ energy of the particles.
Potential Energy
The Sun transfers energy to the atmosphere primarily by _____.
Radiation
The Sun's energy reaches the earth by _________________.
Radiation
Sweat evaporating from the skin cools the body because so much heat is removed while it evaporates.
Result from water having a high specific heat.
The speed of molecules is indirectly related to a measurement called _____________.
Temperature
Five-gram samples of copper and aluminum are at room temperature. Both receive equal amounts of energy due to heat flow. The specific heat capacity of copper is 0.09 cal/g°C, and the specific heat capacity of aluminum is 0.22 cal/g°C.
The copper will get hotter than the aluminum.
What will happen as an object receives energy due to heat flow?
The molecules will move faster.
Specific heat capacity
The quantity of energy that must be absorbed to raise the temperature of a material 1°C.
Temperature
The speed of molecules is indirectly related to a measurement.
What is the predicted result when two different materials of equal mass absorb the same amount of energy by heat flow?
The temperature of both materials will increase the same amount., The temperature of both materials will decrease the same amount., The temperature of the material with the highest specific heat will increase the most., or The temperature of the material with the lowest specific heat will increase the most.
Internal energy
The total kinetic and potential energy of the molecules of an object.
What is the role of the air spaces in insulating materials?
They trap heat in the spaces. They puts gaps between the particles to slow down conduction. They dissipate energy faster. The make the material thicker so energy has to travel a further distance. Allow electrons to move around more freely
External Combustion engine
Train Locomotives, steam engines, steamed-powered paddle boats, coal-fired and nuclear power plants.
Heat flow due to convection could occur in which of the following?
a lake the air in a room the air outside a cement sidewalk
thermal conductivity
a physical property of materials that relates its ability to conduct thermal energy
R-value
a standardized rating for insulating materials
Portland, Oregon, has an average of 240 cloudy days per year. Which heating system would be the least likely choice for this environment?
active solar heat
Which of the following could not be a source of energy for a heat pump?
air pond ground fire
Air space are used in insulation because ____________.
air is a poor conductor.
insulation
any material that reduces loss of energy due to heat flow.
Until the late 1800s, what source was used to heat most homes?
biomass
The transfer of energy by heat flow through a substance is accomplished by _____.
conduction convection radiation all of the above
The total amount of energy in the universe is ________.
constant
As refrigerant passes through the expansion valve, it ______.
cools down
Intake Stroke
draws the fuel mixture into the cylinder.
In a refrigerator or cooling system, a(n) ______ controls the flow of fluid from a high pressure area to a low pressure area.
expansion valve
A piece of wood and a piece of steel are at the same temperature; however, the steel feels hotter. This is because the steel has _______________________.
greater thermal conductivity.
A material with a ______ R-value is a better insulator.
higher
Which type of heat source is the cleanest?
hot water radiant heat
Power Stroke
ignites the fuel and causes the product gases to push against the pistons.
One of the fundamental principles used in an internal combustion engine is that hot gases occupy ________ space than cool gases or liquids.
more
During the refrigeration cycle, warm gases are made even hotter due to _____.
pressurization
Compression Stroke
pressurizes the fuel mixture.
A thermos bottle _____.
reduces energy loss due to radiation, reduces energy loss due to conduction, reduces energy loss due to convection
What is the most commonly used method of food preservation today?
refrigeration
Absorption of energy into the refrigerant causes a phase change from _____.
solid to liquid liquid to vapor vapor to liquid liquid to solid
What has the greatest entropy?
steam
A thermostat is able to control the heating systems in a home by using which of the following properties of metals?
thermal expansion and contraction freely moving electrons high densities high melting points
The main reason ice blocks became unpopular for cooling food was _____.
unsanitary sources of ice.
In the process of cooling air inside the refrigerator, the refrigerant _____.
vaporizes
thermal equilibrium
when two materials in contact are at the same temperature.
