The variation in the pressure of helium gas, measured from its equilibrium value, is given by ΔP = 2.9 × 10−⁵ cos (6.20x − 3 000t) where x and t have units m and s, and ΔP is measured in N/m². Determine the frequency (in Hz) of the wave. A) 1 500 B) 477 C) 1.01 D) 0.32 E) 239

Question

Quizplus · Accepted Answer

The frequency of the wave is given by the coefficient of t in the argument of the cosine function, which is 3,000/6.20 = 483.87 Hz. However, this is not the answer. The actual frequency of the wave is given by dividing the angular frequency by 2π:
f = ω/2π = 6.20/2π ≈ 0.986 Hz ≈ 0.99 Hz (rounded to two significant figures). Therefore, the best choice is (B) 0.99.

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