# A level Thermal Physics Edexcel

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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)
• 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
• 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
• 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
• Charles's law
• The density of an ideal gas at constant pressure varies inversely with the temperature.
• V & T
• 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
• 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