# Orbital vs. Angular speed

Is there a difference between orbital speed and angular speed when an object or star is considered to be in a circular motion around another?

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Welcome, might want to post your Q in the proper area.. Welcome anyway.. Welcome, might want to post your Q in the proper area.. Welcome anyway.. Thanks!

Depends if its a homework question or a general question. Respectively, homework or astronomy sections would work.

I would do a search here. I am sure this question has been asked about 3 million times! Electron Spin

Drakkith
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Welcome to PF!

Thanks!
I've moved the thread to the General Physics forum.

• Electron Spin
Depends if its a homework question or a general question. Respectively, homework or astronomy sections would work.

I would do a search here. I am sure this question has been asked about 3 million times! Electron Spin
Thank you! I kinda found a way to figure it out and I found the right answer to what I was looking for, so yeah thanks!

Welcome to PF!

I've moved the thread to the General Physics forum.
Thank you!

• Electron Spin
Is there a difference between orbital speed and angular speed when an object or star is considered to be in a circular motion around another?
- Orbital speed means the speed transverse to the orbit. It is speed in the normal usage: distance travelled per unit time. It has units like m/s. For a circular orbit it is the circumference over the orbital period.
- angular speed differs in that it is the angle travelled per unit time. It has units like rad/s. For a circular orbit it is 2 π / the orbital period. Note: Since it is "transverse to the orbit" the direction at any point in time is well defined and this is often called orbital velocity.

The two are related by the radius of the orbit. For a circular orbit of radius r
Orbital speed = r * angular speed.

Caveat: if you are hearing both these phrases be careful that the speaker is using them both in reference to the same rotational motion. They might be using one in reference to the orbit and the other in reference to the spin or something like that.