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Study guide: Thermal Physics
Study guide: Thermal Physics
SG13_ThermalPhysics.pdf13 Temperature, Kinetic Theory, and the Gas Laws
13 Temperature, Kinetic Theory, and the Gas Laws
Students should be able to distinguish between temperature and heat.
Students should be able to distinguish between temperature and heat.
Temperature:
Temperature:
Define temperature (13.1)
Define temperature (13.1)
What is temperature and how do we measure the temperature of an object?
What is temperature and how do we measure the temperature of an object?
Convert temperatures between the Celsius, Fahrenheit, and Kelvin scales (13.1)
Convert temperatures between the Celsius, Fahrenheit, and Kelvin scales (13.1)
Temperature is defined as the average KE of the particles. Depends on average speed only of particles (atoms or molecules)
A bucket of water at 50o has the same temperature as a cup of water at 50o
Thermal Energy:
Thermal Energy:
What is thermal energy?
What is thermal energy?
Define thermal energy (13.4)
Define thermal energy (13.4)
Average KE and the mass of the particles Depends on speed and the mass of the particles.
A bucket at 50o has more thermal energy than a cup at 100o
Bucket of $50 bills has more money than a cup of $100’s.
While the particles are going faster in the cup, there are so many more in the bucket.
Heat:
Heat:
Distinguish between temperature and heat.
Distinguish between temperature and heat.
Transfer of energy between objects that have different temperatures.
The direction of heat flow depends on temperature. From hot objects (more energy) to cold objects (less energy).
The speed of the heat flow depends on ...
Kinetic Molecular Theory:
Kinetic Molecular Theory:
What is the kinetic molecular theory (or particle theory)?
What is the kinetic molecular theory (or particle theory)?
Gas molecules collide with each other and their surroundings. Within a sample of gas we find that:
there is a large number of gas molecules (N) moving in random directions and a variety of speeds.
the particles are far apart, with the separation distances being vast compared to the diameter of each particle.
the particles obey laws of mechanics. They attract each other, but we ignore this since the speeds and KE are huge (electrostatic attraction <<< KE motion).
collisions with each other and container walls are assumed to be perfectly elastic. Conservation of momentum and KE.
Describe the distribution of speeds of molecules in a gas (13.4)
Describe the distribution of speeds of molecules in a gas (13.4)
Are all particles in a gas sample moving at the same speeds?
Are all particles in a gas sample moving at the same speeds?
The higher the temperature the faster the molecules move. The particles vary in speed, so we can only measure an average.
Half will be going faster and half slower than the average.
Average KE reflects this speed.
Average KE reflects this speed.
Describe the relationship between the temperature of a gas and the kinetic energy of atoms and molecules (13.4)
Describe the relationship between the temperature of a gas and the kinetic energy of atoms and molecules (13.4)
Calculate the kinetic energy of a gas molecule, given its temperature (13.4)
Calculate the kinetic energy of a gas molecule, given its temperature (13.4)
Pressure:
Pressure:
How does the speed of the particles affect the pressure on the walls of the container?
How does the speed of the particles affect the pressure on the walls of the container?
Universal Gas Law:
Universal Gas Law:
State the ideal gas law in terms of molecules and in terms of moles (13.3)
State the ideal gas law in terms of molecules and in terms of moles (13.3)
Use the ideal gas law to calculate pressure change, temperature change, volume change, or the number of molecules or moles in a given volume (13.3)
Use the ideal gas law to calculate pressure change, temperature change, volume change, or the number of molecules or moles in a given volume (13.3)
Use Avogadro’s number to convert between number of molecules and number of moles (13.3)
Use Avogadro’s number to convert between number of molecules and number of moles (13.3)
Express the ideal gas law in terms of molecular mass and velocity (13.4)
Express the ideal gas law in terms of molecular mass and velocity (13.4)
Static Problems:
Static Problems:
Changing Problems:
Changing Problems:
Boyle’s Law:
Charles’ Law:
Combined Law:
14 Heat and Heat Transfer Methods
14 Heat and Heat Transfer Methods
Specific Heat Capacity:
Specific Heat Capacity:
What is the specific heat capacity and how does it affect transfer of heat energy?
What is the specific heat capacity and how does it affect transfer of heat energy?
Mechanical Equivalent of Heat Lab
Mechanical Equivalent of Heat Lab
http://www.thephysicsaviary.com/Physics/Programs/Labs/MechanicalEquivalentOfHeatLab/
15 Thermodynamics
15 Thermodynamics
Thermodynamic systems and environment:
Thermodynamic systems and environment:
How do we define a thermodynamics system?
How do we define a thermodynamics system?
Think of the amount of energy in universe as constant. But, energy can be added to or subtracted from a system (engine, etc.). Energy comes from or goes to the greater universe (environment). Energy can transfer between systems. A ball colliding with another can transfer energy to that ball. Energy can change forms. If you calculate potential energy that energy can change into kinetic energy, electrical energy, thermal energy, etc.
Internal Energy:
Internal Energy:
Where does the internal energy of a system come from?
Where does the internal energy of a system come from?
All matter has some amount of energy. Objects feel warm to the touch (internal energy: due to heat content or thermal energy of the object) caused by vibration of atoms that make up the object. If energy is added to an object it can start moving or become hotter. If energy is subtracted it can slow down or become colder.
Heat Transfer:
Heat Transfer:
Discuss the different methods of heat transfer (14.4)
Discuss the different methods of heat transfer (14.4)
What are some ways in which heat (thermal energy) is transferred from one object/system to another?
What are some ways in which heat (thermal energy) is transferred from one object/system to another?
Heat transfer occurs in one of three ways.
Conduction: Objects touch transferring energy.
http://www.thephysicsaviary.com/Physics/Programs/Labs/HeatTransferGasesLab/
Convection: Fluids (gases & liquids) carry heat as they flow. Hot air or water rises. Convection currents.
DEMO: Convection box
Radiation: Electromagnetic radiation, as in infrared frequencies of light. Why does a thermos have an inner container separated from the outer by a vacuum? Why is the inside reflective?
http://www.thephysicsaviary.com/Physics/Programs/Labs/RadiantEmission/
Define thermal equilibrium (13.1)
Define thermal equilibrium (13.1)
State the "zeroth law of thermodynamics" (13.1)
State the "zeroth law of thermodynamics" (13.1)
Define heat as transfer of energy (14.1)
Define heat as transfer of energy (14.1)
The student is able to make predictions about the direction of energy transfer due to temperature differences based on interactions at the microscopic level.
The student is able to make predictions about the direction of energy transfer due to temperature differences based on interactions at the microscopic level.
Observe heat transfer and change in temperature and mass (14.2)
Observe heat transfer and change in temperature and mass (14.2)
Calculate final temperature after heat transfer between two objects (14.2)
Calculate final temperature after heat transfer between two objects (14.2)
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