Question

Given that the acceleration due to gravity at the surface of Mars is about 0.38 of what it is on Earth and that Mars' radius is 3400 km, determine the mass of Mars.

Answer 1

we have:\[g={GM\over R^2}\implies g\propto{M\over R^2}\\
{g_E\over g_M}={M_E\over M_M}\times{R_M^2\over R_E^2}
\]

Answer 2

g_E = acc due to gravity of Earth
g_M = that due to Mars
M_E = mass of E
M_M=mass of M
R_E=..
R_M=...

Answer 3

Which equation do I use?