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

1. Nov 23, 2012

### vipson231

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

1. The problem statement, all variables and given/known data

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(all the formulas in the attachment too)

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2. Nov 23, 2012

### Mandelbroth

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

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

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 $\sum{\vec{F}} = m\vec{a}$.

3. Nov 23, 2012

### vipson231

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

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! =))