1. k = 1/9 can't possibly be right. That's what you'd get if the LHS's were equal, but they're not. Can you show your work?

Weight is the gravitational force acting on a mass, so it is a force. As to deriving the W = mg equation from the gravitational force equation, just set F = W, and combine the two equations in post # 8.

2. Originally Posted by Ackbeet
k = 1/9 can't possibly be right. That's what you'd get if the LHS's were equal, but they're not. Can you show your work?

Weight is the gravitational force acting on a mass, so it is a force. As to deriving the W = mg equation from the gravitational force equation, just set F = W, and combine the two equations in post # 8.
I get something different now. [LaTeX ERROR: Convert failed] so M'=13/630M

3. Hmm. I get

$\dfrac{700}{130}=\dfrac{71.43\,G\,m_{\text{earth}} }{r_{\text{earth}}^{2}}\cdot\dfrac{(3r_{\text{eart h}})^{2}}{71.43\,G\,m_{\text{planet}}}=\dfrac{9m_{ \text{earth}}}{m_{\text{planet}}}\dots$

I think your 9 is dividing when it should be multiplying, or vice versa.

4. Originally Posted by Ackbeet
Hmm. I get

$\dfrac{700}{130}=\dfrac{71.43\,G\,m_{\text{earth}} }{r_{\text{earth}}^{2}}\cdot\dfrac{(3r_{\text{eart h}})^{2}}{71.43\,G\,m_{\text{planet}}}=\dfrac{9m_{ \text{earth}}}{m_{\text{planet}}}\dots$

I think your 9 is dividing when it should be multiplying, or vice versa.
yes your right. Sorry this has been really terrible.

5. So, are you all set, then?

6. Originally Posted by Ackbeet
So, are you all set, then?
Yes thanks

7. You're welcome. Hope things go better for you!

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