Temperature and Matter 
Solids
The stress on a material is defined as the force acting per unit cross-sectional area of the material.
The tensile stress is given by: σ = F/A
The strain of a material sample is defined as the extension produced per unit length.
The tensile strain is given by: e = Δx/x
- where x is the length and Δx is the extension
The Youngs Modulus also known as modulus of elasticity is defined as:E = stress/strain
- A more simplified version of this is: E = Fx/(ΔlxA)
Elastic Energy is given by:E = 1/2k(Δx)2
Thermal Properties
The celcius scale is defined by: θ = T -273.15
- where T is the temperature in absolute kelvin
Heat Capacity is given by: C = ΔQ/ΔT
- where ΔQ is the heat flow into the body
- ΔT is the change in temperature
Specific heat capacity is given by: c = ΔQ/mΔT
Specific latent heat is given by: l = ΔQ/m
Ideal gases
Boyle's Law states that the pressure(p) of a fixed mass of gas at constant temperature is inversely proportional to its volume(V)
Boyle's Law can be expressed as: pV = constant
Charles' Law states that the volume of a fixed mass of gas at constant pressure is directly proportional to its absolute temperature(T)
Charles' Law can be expressed as: V/T = constant
The Pressure Law states that the pressure of a fixed mass of gas at constant volume is directly proportional to its absolute temperature.
The Pressure Law can be expressed as: p/T = constant
The ideal gas equation is:pV = nRT
- where n = no. of moles in gas
- R is the universal molar gas constant = 8.31 mol-1K-1
The number of atoms in 12g of carbon-12 is called Avogadros Constant NA
NA = 6.023*1023mol-1
The Relative Molecular Mass is:Mr = (mass of a molecule of the substance / mass of the carbon-12 atom)*12
The Molar mass is given by: Mm = Mr*10-3
The number of moles in a given mass of gas is given by:n = M/Mm
- where M is the mass of the gas
The pressure exerted by an ideal gas is: p = 1/3ρc2
- where c2 is the mean squared velocity
The Work done by a gas is:ΔW = pΔV
The First law of Thermodynamics is:ΔQ = ΔU+ΔW
- where ΔQ = heat energy supplied to a system, or flowing out of it (+ when heat supplied)
- ΔU = change of internal energy of the system (+ if external work done by system)
- ΔW = work done by or on the system (+ if internal energy of system increases)
Heat Transfer
Thermal conduction is the process by which heat flows from the hotter to the colder regions of a body without any transfer of the material itself
The Thermal conduction equation is given by:ΔQ/Δt = -kA(ΔT/Δx)
- where ΔQ/Δt is the rate of transfer of energy
- k is a constant which depends on the material-called thermal conductivity
- ΔT/Δx is the temperature gradient
The Thermal resistance is given by:RT = Δx/kA