Question

The mass and diameter of a planet have twice the value of the corresponding parameters of earth. Acceleration due to gravity on the surface of the planet is
A. `9.8 m//s^(2)`
B. `19.6 m//s^(2)`
C. `980 m//s^(2)`
D. `4.9 m//s^(2)`

Answer 1

Correct Answer - D
`because g = (GM)/(R^(2)) " " therefore (g_(P))/(g_(E ))=(G(M_(P)))/((R_(P))^(2))xx((R_(E ))^(2))/(G(M_(E )))`
`= ((M_(P))/(M_(E )))((R_(E ))/(R_(P)))^(2)`
`because M_(P)=2M_(e )` and `R_(P)=2R_(e )`
`therefore (g_(P))/(g_(E ))=2xx((1)/(2))^(2)=(1)/(2)`
`therefore g_(P)=(g_(E ))/(2)=(9.8)/(2)=4.9 m//s^(2)`