The variation in the pressure of helium gas, measured from its equilibrium value, is given by
ΔP = 1.5 x 10-5 cos(7.6x - 1200t) where x and t have units m and s, and ΔP is measured in N/m2.Determine the wavelength (in m) of the wave.

A.) 0.41
B.) 382
C.) 600
D.) 0.83
E.) 0.93

Question

The variation in the pressure of helium gas, measured from its equilibrium value, is given by
ΔP = 1.5 x 10-5 cos(7.6x - 1200t) where x and t have units m and s, and ΔP is measured in N/m2.Determine the wavelength (in m) of the wave.

A.) 0.41
B.) 382
C.) 600
D.) 0.83
E.) 0.93

anonymous · Answer

$\cos(\color{red}{7.6}x-\color{blue}{1200}t)$
focus on these two values. The first tells you the phase velocity of the wave as it physically moves (hence it's next to an $x$), and the second tells you the frequency of the wave (hence the $t$)

anonymous · Answer

Recall frequency $\nu=\frac1\lambda$ where $\lambda$ is the wavelength.