It deals with the exchange of heat energy between bodies and the conversion of heat energy into mechanical energy and vice-versa.
Heat
Thermal energy is transmitted from one body to another. Heat is energy in transit.
Temperature
It is a measure of an object’s internal energy.
Kinetic Theory of Gases
It relates to the macroscopic properties of gases such as pressure, temperature, etc.
Every gas consists of small particles known as molecules.
The gas molecules are identical but different from those of another gas.
The volume of molecules is negligible compared to the volume of gas.
The density of a gas is constant at all points.
Consequently, pressure is exerted by gas molecules on the walls of the container.
No attractive or repulsive force exists between the gas molecules.
The Ideal Gas Law
Pv = nRT
P = pressure
V = volume
n = no. of moles
R = Gas constant
T = temperature
Average Kinetic Energy
The pressure exerted by N molecules of gas in a container is related to the average kinetic energy.
K avg = 3/2 kb T
K avg = average kinetic energy
kb = Boltzmann’s constant
T = temperature
Root mean square velocity
It gives us a type of average speed that is easy to calculate from the temperature of the gas.
vrms = √3 kb T/ m
vrms = root mean square velocity
kb = Boltzmann’s constant
T = temperature
m = mass
The Maxell-Boltzmann Distribution
The Kinetic theory of gases applies to a large number of particles.
Some molecules will be moving faster than average and some much slower.
Heat Engines
It is a device which uses heat to produce useful work
Convection
The movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat
Radiation
Radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.
Zeroth law of thermodynamics
If objects 1 and 2 are in thermal equilibrium with Object 3, then Objects 1 and 2 are in thermal equilibrium with each other.
First law of thermodynamics
It is a special case of the law of conservation of energy that describes processes in which only internal energy changes and the only energy transfers are by heat and work.
∆ U = Q + W
Q = heat added
W = work done by the system
∆ U = change in internal energy
work done
it is used to calculate work done.
Isothermal Process
Temperature remains constant.
Adiabatic process
no transfer of heat
Isobaric process
pressure remains constant
Isochoric process
volume remains constant.
Second law of thermodynamics
It describes how systems evolve over time.
Entropy
It is associated with a state of randomness, disorder, or uncertainty.
Conduction
Heat conducts from one point to another only if there is a temperature difference between the two objects.