Gravity on a new planet with same density – Rankers Physics
Topic: Gravitation
Subtopic: Acceleration Due to Gravity and its variation

Gravity on a new planet with same density

Imagine a new planet having the same density as that of earth but it is $3$ times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is $g$ and that on the surface of the new planet is $g'$, then:

(2005)

$g' = 3g$
$g' = \frac{g}{9}$
$g' = 9g$
$g' = \frac{g}{3}$

Solution:

Acceleration due to gravity in terms of density is $g = \frac{4}{3}\pi \rho G R$. Since density $\rho$ is constant, $g \propto R$. For a planet $3$ times bigger in size ($R' = 3R$), the new gravity is $g' = 3g$.

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