Posted by **Angelina** on Thursday, February 23, 2012 at 8:21pm.

A planet has two satellite moons. Moon X has an orbital period of 2.13 days. Moon Y has an orbital period of about 3.53 days. Both moons have nearly circular orbits. Use Kepler's third law to find the distance of each satellite from the planet's center. The planet's mass is 2.0 10^26 kg.

Moon X km?

Moon Y km?

I have posted this earlier but didn't get a respond am sorry to re-post it but I really need help with this!

Physics - drwls, Sunday, February 19, 2012 at 12:27pm

The Kepler's law formula you need to use is:

T²/R³ = 4π²/(GM)

M is the mass of the planet, in kg

G is the universal constant of gravity, which is easily found online.

T is the period in seconds

Tx = 1.840*10^5 s

Ty = 3.050*10^5 s

R is the orbit radius in meters. Do the calculations of R for planets X and Y, one at a time.

Ok i tried this but i still cant get the answer right I don't understand it :(

- Physics -
**bobpursley**, Thursday, February 23, 2012 at 8:46pm
T^2/R^3=4PI^2/GM

R= cubrt ( T^2 G*mass/4PI^2)

solve for R, knowing period T, G, Mass.

Do that for each moon.

- Physics -
**Angelina**, Thursday, February 23, 2012 at 9:00pm
Ok so this is what i did cubrt(2.13^2(6.67x10^-11)(2.0x10^26))/(4pi2)=R which is 1159307512 but then thats wrong so i don't know what i am doing wrong?

## Answer this Question

## Related Questions

- Physics - A planet has two satellite moons. Moon X has an orbital period of 2....
- physics - A planet has two satellite moons. Moon X has an orbital period of 2.13...
- Physics I am lost please help - A planet has two satellite moons. Moon X has an ...
- Physicsss - A planet has two satellite moons. Moon X has an orbital period of 2....
- Physics - A planet has two satellite moons. Moon X has an orbital period of 2.13...
- Physics 1111: Orbitals and Distance - A planet has two satellite moons. Moon X ...
- Physics to bobpursley or any1 else who knows this - A planet has two satellite ...
- Physics - Astronomers can calculate the mass of a planet by using the orbital ...
- physics - (a) One of the moons of Jupiter, named Io, has an orbital radius of 4....
- physics - The period of a satellite is the primary way that the mass of planets ...

More Related Questions