Answer
a) $T=12h$
b) $v=3.9\frac{Km}{s}$
Work Step by Step
(a) We know that
$T=(\frac{2\pi}{\sqrt{GM_E}})r^{\frac{3}{2}}$
We plug in the known values to obtain:
$T=\frac{2\pi}{\sqrt{6.67\times 10^{-11}(5.97\times 10^{24})}}(2.0\times 10^7+6.37\times 10^6)$
$T=43000s=12h$
(b) We can find the orbital speed as
$v=\frac{2\pi r}{T}$
We plug in the known values to obtain:
$v=\frac{2\pi(2.637\times 10^7)}{4.3\times 10^4}$
$v=3900\frac{m}{s}$
$v=3.9\frac{Km}{s}$
