On a planet whose size is the same and mass four times as that of our earth, find the amount of work done to lift `3 kg` mass vertically upwards through `3 m` distance on the planet. The value of `g` on the surface of earth is `10 ms^(-2)`

Explanation

Here, `R_(p) = R_(e), M_(p) = 4 M_(e), m = 3 kg, h = 3 m, g_(e) = 10 m//s^(2)`.
On the surface of earth, `g_(e) = (GM)/(R_(e)^(2))`
On the surface of planet, `g_(p) = (GM_(p))/(R_(p)^(2)) = (G4M_(e))/(R_(e)^(2)) = 4 (GM_(e))/(R_(e)^(2)) = 4g_(e) = 4 xx 10 = 40 ms//^(2)`
Work done `= m g_(p)h = 3 xx 40 xx 3 = 360 J`