Answer
(a) $0.56Hz$
(b) $2.2m/s$
Work Step by Step
(a) We can find the required frequency as
$f=\frac{1}{2\pi}\sqrt{\frac{g}{L}}$
We plug in the known values to obtain:
$f=\frac{1}{2(3.14)}\sqrt{\frac{9.8}{0.78}}$
$f=0.56Hz$
(b) We know that
$v=(\frac{nh}{\pi m})^{\frac{1}{2}}(\frac{g}{l})^{\frac{1}{4}}$
We plug in the known values to obtain:
$v=[\frac{(1.0\times 10^{33})(6.63\times 10^{-34})}{(3.14)(0.15)}]^{\frac{1}{2}}[\frac{9.80}{0.88}]^{\frac{1}{4}}$
$v=2.2m/s$
