Question

A planet of mass m moves round the sun of mass M in a circular orbit of radius R with an angular velocity w. Show that in circular orbit of radius 4R round the sun,the angular velocity decreases to w/8

Answer 1

Here it is.
Hope it helps

Answer 2

W
$w= \frac{2\pi}{w} \\ f = mrw { }^{2} = mr. \frac{2\pi}{w } = \frac{4\pi {}^{2} }{t {}^{2} } mr$
Apply Kepler laws
$t {}^{2} directly \: proprtion \: to \: r {3}$