Consider a hypothetical planet with a mass equal to half that of Earth and radius is onethird that of Earth. If g is the acceleration due to gravity on Earth, the acceleration due to gravity on the planet will be:

Let us consider the mass of planet is M.

The radius of earth is R.

Hence, the gravitational acceleration of the earth is calculated as -

$$g = G\frac{M}{R^2}$$

Here, G is the universal gravitational force constant.

Hence, the acceleration due to gravity on this planet will br

                                             $$g = G\frac{\frac{M}{2}}{\left(\frac{R}{3}\right)^2}$$

                                               =$$G\frac{M}{2}\times \frac{9}{R^2}$$