Thermal Physics
Thermodynamics
Heat Pump
A refrigerator or an air-conditioner unit is an example of a heat pump
- Heat pumps normally flow from cold to hot
QH = QC + W
Heat transfers from the cold reservoir Qc into the hot resavour
This requires W, which is converted to heat
Therefore QH consist of the heat flowing out of the cold reservour QC and the work done on the heat pump W.
QH = Heat transfer to the hot reservoir
Qc = heat transfer to a cold reservoir
W = Work done to increase heat
Gasses
PV = NkT
P= Pressure (Pa)
V= Volume (m3)
N= Number of molecules
K= Boltzmann constant
T= Temperature (k)
P1V1 = p2V2
P1 = 125 kPa
P2 = 100 kPa
V1 = 200cm3
V2 = (125 x 200)/ 100 = 250cm3
Assuming the temperature remains constant
Isothermal process: A change in the system i.e. Composing or expanding the gas where the temperature does not change.
Adiabatic process: An adiabatic process is one where no heat enters or leaves the system (opposite to an isothermal process because the temperature will change).
Laws of thermodynamics
Efficiency = W/Qin
Qin = how much comes in
W= work
Efficiency = 1 - Qout/Qin
Efc = 1 - TC/TH
Tc = Temperature of cold reservoir
TH = Temperature of hot reservoir
Kalvin = +273.15
What U, Q and W mean in relation to the human body
W - translates to heavy exercise and even sleep
Q - Qin is the food we eat and that food is used to provide us with energy and in tern translates into work.
U - Your body storing food to convert into energy at a later date is and example of internal energy