Question

For moon, its mass is 1/81 of earth mass and its diameter is 1/3.7 of earth dia. If acceleration due to gravity at earth surface is 9.8 m/s² then at moon its value is :

(1) 2.86 m/s² 

(2) 1.65 m/s² 

(3) 8.65 m/s² 

(4) 5.16 m/s² 

Answer 1

Correct Answer is; (2) 1.65 m/s² 

g = GM/R²  or g ∝ M/R² 

g_M = M_M/M_E x (R_E/R_M)2 cg_E.

= 1/8 x (3.7)² x 9.8 = 9.8/6 = 1.65 m/s²