Question

I will be so thankful if u answer correctly!!​

Answer 1

(C) 200 N

Explanation:

The acceleration due to gravity on earth $g_{E}$ is given by

$g_{E} = G\dfrac{M_{E}}{R_{E}^{2}}$

where $G$ = universal gravitational constant

$\:\:\:\:\:\:\:\:\:\:\:\:M_{R}$ = mass of the earth

$\:\:\:\:\:\:\:\:\:\:\:\:R_{E}$ = radius of the earth

Planet Krypton has twice the mass of earth and 3 times the radius so its acceleration due to gravity $g_{K}$ is

$g_{K} = G\dfrac{M_{K}}{R_{K}^{2}}$

$\:\:\:\:\:\: = G\dfrac{(2M_{E})}{(3R_{E})^{2}}$

$\:\:\:\:\;\:= (\dfrac{2}{9})G\dfrac{M_{E}}{R_{E}^{2}}$

or

$g_{K} = (\dfrac{2}{9})\:g_{E}$

If we multiply both sides by Superman's mass, we get his weights on both planets:

$mg_{K} = (\dfrac{2}{9})\:(mg_{E})$

$W_{K} = (\dfrac{2}{9})\:W_{E} = (\dfrac{2}{9})(900\:N)= 200\:N$