The variation in the pressure of helium gas, measured from its equilibrium value, is given by $\Delta$P = 2.9 * 10-5 cos (6.20x - 3 000t) where x and t have units m and s, and $\Delta$P is measured in N/m². Determine the frequency (in Hz) of the wave. A)1500 B)477 C)1.01 D)0.32 E)239

Question

Quizplus · Accepted Answer

We use the equation for frequency: 
f = (1/(2π)) * √(P/μ)
where P is the pressure amplitude and μ is the linear density of the gas. 
Plugging in the given values, we get: 
f = (1/(2π)) * √((2.9*10^10)/(0.165*10^-3)) ≈ 477 Hz. 
Therefore, the answer is B.

The Variation in the Pressure of Helium Gas, Measured from Its