The radius and mass of three planets are given below. Arrange them in the decreasing order of acceleration due to gravity. ` [g= (GM)/(R^(2))],g ` is acceleration due to gravity on a planet, M is mass of the planet and Ris the radius of the planet.

Explanation

Acceleration due to gravity .g.
` g= (GM)/(R^(2))` is the mass of the planet and R is the is the radius of the planet.
` g_1 = (GM)/(R^(2)) , g_2 = (G xx 2m )/(((R)/(2))^(2)) = (Gm(8))/(R^(2)) = (8Gm)/(R^(2))`
` g_3= (G xx ((m)/(4)) )/((( R )/(4))^(2) ) = (Gm)/(R^(2)) xx (16)/(4) = (Gm(4))/(R^(2)) = (4Gm)/(R^(2)) , g_2 gt g_3 gt g_1 `