Question

A planet having a same density as that of earth but its radius is 4 times bigger than the radius of

earth. If the acceleration due to gravity on the surface of earth is g and that on the surface of the

planet is g’, then.

(A) g’ = g/4 (B) g’ = 16 g

(C) g’ = 9 g (D) g’ = 4 g​

Answer 1

Answer: 3g

Explanation:

If the mass and radius of the new planet be

M′and R',then for same density as earth,R′ =3R & M′ =27M [MαV, where VαR³ ]

Now for Earth,

g=GM/R² →(1)

and for new planet,g′= GM'/R′2

= G(27M)/(3R)²

= G(27M) =3(GM/ R²)=3g.