Question

A spherical planet has a mass $M_p$ and diameter $D_p$. A particle of mass $m$ falling freely near the surface of this planet will experience an acceleration due to gravity, equal to

• A. $\frac {4GM_p}{D_p^2}$
• B. $\frac {GM_pm}{D_p^2}$
• C. $\frac {GM_p}{D_p}$
• D. $\frac {4GM_pm}{D_p^2}$

Answer 1

Answer: (A)

$\frac {4GM_p}{D_p^2}$

Answer 2

$g =\frac{ GM _{ p }}{ R _{ p }{ }^{2}}$ where $R _{ p }= D _{ p } / 2$