Question

For a certain transverse wave, the distance between two successive crests is 1.20 m, and eight crests pass a given point along the direction of travel every 12.0 s. calculate the wave speed.

Answer 1

The distance between two successive crests of the wave corresponds to the wavelength of the wave, so:
$\lambda=1.20 m$
8 Crests of the wave pass a given point in t=12.0 s. This means that the frequency of the wave (the number of oscillations per second) is given by
$f= \frac{8}{12.0 s}=0.67 Hz$

And now we can calculate the speed of the wave, which is given by the product between wavelength and frequency:
$v=\lambda f = (1.20 m)(0.67 Hz)=1.79 m/s$