If the mass of the planet is 1.38 x 10^25 kg and its radius is 4.30 x 10^7 m

[vipson231]

If the mass of the planet is 1.38 x 10^25 kg and its radius is 4.30 x 10^7 m...

Homework Statement

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(all the formulas in the attachment too)

I don't know how to start this question Please help -[

 

[Mandelbroth]

I think that you are thinking about this too hard.

$F_{gravity} = G\frac{m_{1}m_{2}}{r^{2}}$

You know G, which is a constant. You know the two masses (the planet and the apple). You know the radius of the planet. Find the force. Then, it's a simple question of $\sum{\vec{F}} = m\vec{a}$.

 

[vipson231]

Oh I think i overlooked the F=Gm1m2/r^2 formula and wasn't able to work with the other formulas that were provided. Thanks for the help! =))