# A level Thermal Physics Edexcel

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- Created by: philippe marr
- Created on: 12-04-13 09:40

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- Thermal Physics
- Heat and Temperature
- Temperature
- Heating an object causes its temperature to rise
- If the average Kinetic energy of the molecules of a substance increases, then it has a higher temperature
- It is the internal energy that determines the temperature

- Heat transfer
- Heating will becomes distributed throughout a substance, with the heat being passed from hotter areas to colder ones.

- Absolute zero is the point when the molecules will no longer be moving at all. (-273 C)

- Temperature
- Specific heat capacity
- Depends on three things
- 1. The amount of heat energy transferred
- 2. The mass of the object
- 3. The Specific heat capacity of the material from which the object is made.

- A material has a given property known as its Specific Heat Capacity, C.
- This is the energy needed to raise the temperature of 1kg of a particular substance by 1K

- }E= mc}temp
- Jkg-1 K-1

- Depends on three things
- Iternal energy
- If we sum the kinetic and the potential energies of a substance, we have measured its internal energy.
- The internal energy is randomly distributed across all the molecules according to the Maxwell-Boltzmann Distribution.

- The Maxwell-Boltzmann distribution
- If we plot the kinetic energy against the number of molecules that have that energy, we get a curved graph called the Maxwell-Boltzmann distribution
- The characteristic shape of the graph shows that:
- There are no molecules with zero energy.
- Only a few molecules have high energies.
- There is no maximum value for the energy a molecule can have.

- The graph is for one specific temperature. As the temp changes so the graph changes.
- Molecular kinetic energy
- 1/2m<c2>=3/2kT
- Were k is the Boltzmann constant, 1.38x10-23 JK-1
- T is temp and it must be in kelvin

- 1/2m<c2>=3/2kT

- Root-Mean-Square Speed
- This has the symbol ?<c2>
- This is the speed associated with the average kinetic energy, 1/2m<c2>
- To find the R.M.S
- First, find the Square of each value
- Then the average of the square values is.
- Finally, take the square root to get the R.M.S speed.

- Boyle's law
- A law stating that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature.
- P & 1/v

- A law stating that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature.
- Charles's law
- The density of an ideal gas at constant pressure varies inversely with the temperature.
- V & T

- The density of an ideal gas at constant pressure varies inversely with the temperature.
- The Pressure law
- For a constant mass of gas at a constant volume, the pressure exerted by the gas is proportion to its absolute temp
- P & T

- For a constant mass of gas at a constant volume, the pressure exerted by the gas is proportion to its absolute temp
- Ideal gases
- 1. the molecules have zero size.
- 2. The molecules are identical.
- 3. The molecules collide with each other and the wall of there container without any loss of energy, in collisions which take zero time.
- 4. The molecules exert no forces on each other, except during collisions.
- 5. There are enough molecules so that statistic can be applied.
- pV=NkT
- pV=nRT
- n is the number of moles of the gas; R is the Universal gas constant, R= 8.31 Jkg-1 mol-1
- pV=NkT
- pV=nRT
- n is the number of moles of the gas; R is the Universal gas constant, R= 8.31 Jkg-1 mol-1

- n is the number of moles of the gas; R is the Universal gas constant, R= 8.31 Jkg-1 mol-1

- pV=nRT

- pV=NkT

- n is the number of moles of the gas; R is the Universal gas constant, R= 8.31 Jkg-1 mol-1

- pV=nRT

- Heat and Temperature

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