The average speed of molecules in an ideal gas is
.
Where
is the molecular weight of the gas,
is the gas constant,
is the gas temperature and
is the molecular speed.

Let
.
.
Consider
.
.
Solve the integral by using parts of integration method.
\Formula for integration by parts :
.
and
.
Consider
.
Apply derivative on each side with respect to
.


.
Consider
.
Apply integral on each side.
\
.
Substitute the corresponding values in
.





Substitute
.




.
Substitute
in
.





Substitute
.





.
.