Converting orbital period from hours to seconds for gravity calculation

[triden]

http://upload.cybermart.ca/2004/hepmesad.gif


I can't decide what to do with this question. I am studying for a final. I converted 24 hours to seconds and tried using the Fg = -gmm/r but I don't think that's going to work...

any leads? Thanks guys

 

[theFuture]

You're on the right track. Think about circular motion, too.

 

[triden]

You're on the right track. Think about circular motion, too.

ok I think I am getting it.

r*(omega)^2 = GM/r^2

then i can cancel the R's to get

Omega^2 = GM/r ?

 

[dextercioby]

ok I think I am getting it.

r*(omega)^2 = GM/r^2

then i can cancel the R's to get

Omega^2 = GM/r ?

Yes,it's correct.To check your answer,though,u should be gettin round about 35000km.

 

[Gamma]

you mean omega^2 = GM/r^3

 

[frankR]

That's one of my favorite problems.

I think the answer is about 24,000mi. Don't forget to subtract the radius of the earth. I always forget to do that!

 

[saltrock]

i Think radius should be (R+r) and use F=GMm/(R+r)^2

 

[dextercioby]

i Think radius should be (R+r) and use F=GMm/(R+r)^2

Why complicate?Use "r" as your length variable (the radius of the trajectory)and then,once u got the result,subtract the mean radius of the Earth which is round about 6371km.