In: Physics
Would the speed of sound in a monatomic gas like helium be the same as it would be in air (primarily a diatomic gas)? Why? Assume that both gases have the same density and exist at the same pressure.
Yes. If the pressure and density of both gases are the same, then the speed of sound must be the same.
No. The energy that goes into molecular bonds in the diatomic gas makes the effective spring constant of the gas different from that of the monatomic gas.
No. It is impossible for both gases to have the same density, so the speed of sound cannot possibly be the same in different gases.
Yes. The oscillating medium in each case can be approximated to be the same.
According to the Newton-Laplace equation speed of sound in gases is given by-
where =adiabatic constant
P=pressure of gas
d=density of gas
For same pressure and temperature ,speed of gas depends upon adiabatic constant while adiabatic gas constant of a gas deoends upon atomicity of gas.
Helium is a monoatomic gas while air is considered as a diatomic gas so adiabatic constant is different for helium and air(it is more for air and less for He).So speed of sound is not same for He and air(It is greater for air and lesser for He).
Adiabatic gas constant depends upon molecular bond presents in the molecule..Molecular bond behave as a spring and the spring constant of this spring is different for diatomic and monoatomic gas...
so in the given options ,second option is correct.