Answer
Please see the work below.
Work Step by Step
(a) We can find the wave number as
$k=\frac{2\pi}{\lambda}$
We plug in the known values to obtain:
$k=\frac{2\pi}{10.8}=0.58m^{-1}$
(b) As $\omega=\frac{2\pi}{T}$
We plug in the known values to obtain:
$\omega=\frac{2\pi}{4.1}$
$\omega=\frac{2\pi}{4.1}=1.5\frac{rad}{s}$
