NEET Physics Notes Mechanics-Behaviour of Perfect Gas and Kinetic-Theory Concept of Pressure
Concept of Pressure
Concept of Pressure
Pressure p exerted by a perfect gas on the walls of container is given by
Here, m = mass of each molecule,
= root mean square velocity of molecules, ρ= density of gas, M = mass of gas enclosed in volume V of container, and E = Total KE of the ideal gas.
Various Speeds of Gas Molecules
- Root mean square speed It is defined as the square root of mean of squares of the speed of different molecules
- Most probable speed It is defined as the speed which is possessed by maximum fraction of total number of molecules of the gas.
- Average speed It is the arithmetic mean of the speeds of molecules in a gas at given temperature.
Degree of Freedom (f)
The term degree of freedom of a system refers to the possible independent motions, system can have
- for monoatomic gas, (f) = 3
- for diatomic gas, (f) = 5
- for triatomic gas, (f ) = 6(non-linear)
- for triatomic (linear) gas, (f) = 7
- for N-atomic molecule (f) = 6N – 3
- for N-atomic linear molecule (f) = 6N – 5