A planet having mass 9 M _ e and radius 4 R _ e , where M _ e and R...

The escape velocity on earth is given by ${V}_{\text{e}} = \sqrt{\dfrac{2G{M}_{e}}{{R}_{e}}}$

Escape velocity for the planet is

$V{'}_{esc} = \sqrt{\dfrac{2G ( 9{M}_{e} )}{4{R}_{e}}} . . . ( i )$

The escape velocity of earth is ${V}_{e} = 11 . 2 \times {10}^{3}m{s}^{- 1}$

From equation (i)

$V{'}_{esc} = \sqrt{\dfrac{9}{4}\left(\dfrac{2G{M}_{e}}{{R}_{e}}\right)} = \dfrac{3}{2} \times 11 . 2 \times {10}^{3}m{s}^{- 1} ⇒ V{'}_{esc} = 16 . 8km{s}^{- 1}$