# Throwing a baseball while standing on an Asteroid

takelgith
Summary:: Between the orbits of Mars and Jupiter, several thousand small objects called asteroids move in nearly circular orbits around the Sun. Consider an asteroid that is spherically shaped with radius
r and density 2100 kg/m^3.

a.
You find yourself on the surface of this asteroid and throw a baseball at a speed of 28
m/s. If the baseball is to travel around the asteroid in a circular orbit, what is the largest radius asteroid on which you are capable of accomplishing this feat??

- For this I equated GMm/r^2 = mv^2/r and solved for r. I used the density to find M.
I got r = √[(28^2)/(2100π)(6.67^-11)]
it says its wrong!

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Homework Helper
- For this I equated GMm/r^2 = mv^2/r and solved for r. I used the density to find M.
I got r = √[(28^2)/(2100π)(6.67^-11)]
it says its wrong!
Can you elaborate on the part where you used the density to find M?

takelgith
Can you elaborate on the part where you used the density to find M? You did it wrong.

So I had M = 2100π R^3.

Then I subbed that into the equation, for which the R got canceled and became R^2 and thus my result.

Homework Helper
So I had M = 2100π R^3
Where does that formula come from?

takelgith
So I had M = 2100π R^3.

Then I subbed that into the equation, for which the R got canceled and became R^2 and thus my result.

Oh shoot! Its supposed to be 4/3piR^3. So M= 2100 *(4/3 pi r^3) right? that should be right??

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