Homework Help: Big anaconda orbiting the planet

1. Oct 13, 2011

paul-g

1. The problem statement, all variables and given/known data
Big anaconda orbiting the planet XYZ-123 in a vertical position (along the radius of the planet and at a constant height). At some point, anaconda folded her in a small bundle. Is its orbit will be circular? He begins to recede from or approach the planet?

2. The attempt at a solution

I know that the anaconda was able to perform the action described in the command have to do some work. It seems to me that it would start by moving away from the planet, but I do not know how to prove it.

2. Oct 13, 2011

WatermelonPig

Is angular momentum conserved?

3. Oct 13, 2011

paul-g

There is no information about it, but I think yes.

4. Oct 13, 2011

Staff: Mentor

Why not choose some numbers for an example and work out a figure for the angular momentum of the snake stretched out (so going from say, radius r1 to radius r2). Then determine at what radius the compact body would want to orbit with that same angular momentum. Compare this and that.

5. Oct 13, 2011

paul-g

I thought to write it this way

$E_{p}=-\frac{GMm}{r}$

$F=ma$

$\frac{GMm}{r^2}=\frac{mv^2}{r}$

$\frac{mv^2}{2}=\frac{GMm}{2r}$

$E_{k}=-\frac{E_{p}}{2}$

$E=E_{k}+E_{p}=\frac{GMm}{2r}-\frac{GMm}{r}$

$E=-\frac{GMm}{2r}$

This applies to the circular orbit, but in our case:

$E_{k}=E_{k_{1}}-W$

$E=E_{k_{1}}-W+E_{p}$

How to prove that the orbit is not circular. This is enough? Snake gave up and will be circulated in the orbit of larger radius, or begin to move away from the planet?

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook