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espen180
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Homework Statement
Determine the speed of sound in argon gas at 30 degrees celcius. Argon is a monoatomic gas with atomic mass 40. Assume adiabatic and ideal gas conditions. The mass of a nucleuon is 1.67*10-27 kg=mp.
Homework Equations
Adiabatic constraint: pVγ=constant.
Ideal gas equation: pV=nRT=NkT
Speed of a sound wave: [itex]v=\sqrt{B/\rho}[/itex]
The Attempt at a Solution
From the adiabatic constraint: [itex]\text{d}p V^{\gamma} + \gamma p V^{\gamma-1} \text{d}V=0[/itex]
[itex]B=-V\frac{\text{d}p}{\text{d}V}=\gamma p[/itex]
Insert into ideal gas equation, using [itex]\rho=\frac{Nm}{V}[/itex] :
[itex]B=\frac{\gamma \rho k T}{m}[/itex]
Finally: [itex]v=\sqrt{\frac{B}{\rho}}=\sqrt{\frac{\gamma k T}{m}}[/itex]
Insert values: m=40*mp=6,68*10-26 kg, k=1.38*10-23 J/K, T=303.15 K, γ=3/5=0.6
This produces the result v=194 m/s.
However, the answer key says the correct value is 323 m/s
I have searched my solution attempt multiple times, unable to find my error. Any help will be greatly appreciated.
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