Calculating Wave Properties: Frequency, Wavelength, and Speed

[anotherperson]

Homework Statement

the displacement of a wave traveling in the negative x-direction is given by
y(x,t)=(5.2cm)cos(5.5x/m+72t/s)

where x is in metres, t is in seconds, calculate:
i)the frequency
ii) the wavelength
iii) the speed of this wave)

The Attempt at a Solution

i have absolutely no idea how do calculate the first 2. i thought you could just read the frequency and wavelength of the equation but this doesn't match my solutions

i know part iii) will be speed=72/5.5= 13 m/s

 

[Apophilius]

Remember that the equation of a wave is y(x,t) = ymsin(kx +- wt). In this case its s(x,t) = smcos(kx +- wt). Your equation above takes the form of the latter. Frequency is related to w by the equation w = 2pi f where f is frequency - so just plug in the w from your equation and solve. Also, k is related to wavelength (I'll label wavelength as y) by the equation k = (2pi)/y. Here you also just need to plug in your values from the equation and solve. And yeah, you're right about the speed. v = w/k.

 

[anotherperson]

this is exactly what i had done but i had used k for w and w for k, that's for the help!

 

[anotherperson]

thanks**