Satelites & Orbits: Find the Orbital Speed

[alex7298]

Homework Statement

A satelite is placed in orbit 6.00x10^5 meters above the surface of Jupiter which has a mass of 1.90x10^27kg and has a radius of 7.14x10^7m. Find the orbital speed of the satelite

Homework Equations

V=sqroot(GM/r)

The Attempt at a Solution

First i added the altitude of the satelite to the radius of Jupiter to find the total orbital radius, then just plugged in numbers to get:

V=sqroot((6.67x10^-11)(1.90x10^27kg)/7.2x10^7m)

That seems like it would be right but my answer is way too big

Any help would be greatly appreciated

 

[tyco05]

A common mistake in these problems is to forget the square root.

Is that what you did?

The answer I got was reasonable using your method.

 

[alex7298]

lol this time i got 4.2x10^4m/s which is the right answer. Maybe i did forget the squre root.
Thanks

I had one more question and it is:
Suppose the surface of a space station is rotating and 35.8m/s. What must be the value of r (radius) for the astronauts to weigh one-half their weight on earth.

I was able to get two equations equal to each other and they are M(V^2/r)=M(g)
Then i rearranged to get V^2/r=1/2g-----> i divided "g" by two because of the half weight thing
but when i solve for r its a super small number
where am i going wrong?

 

[tyco05]

It seems right to me... re-check your solving for r.

Did you remember to square the velocity? :)

What do you mean by "super small number"?

 

[alex7298]

gah i made another stupid mistake
i did (1/2g)/V^2 for some reason
i have the right answer now though
lol I am having an off night
thansk tough