Question

An exoplanet having equal mass and radius one-third of the Earth is discovered by the scientists. Calculate the value of acceleration due to gravity on that exoplanet, if its value on Earth is 'g'.

• A. 3g
• B. 9g
• C. $\frac{g}{3}$
• D. $\frac{g}{9}$

Answer 1

The correct option is B 9g

Given: Acceleration due to gravity on Earth = g
Let mass and radius of Earth be 'M' and 'R', respectively, then
$Massofexoplanet=M$
$Radiusofexoplanet=\frac{R}{3}$

Now,
$g_{earth}=\frac{GM}{R^2}$
$g_{exoplanet}=\frac{GM}{(R/3{)}^2}$
Thus,
$g_{exoplanet}=\frac{9GM}{R^2}$
$g_{exoplanet}=g_{earth}=9g$