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### Course: Mechanics (Essentials) - Class 11th>Unit 10

Lesson 2: Are all of Saturn's rings moving at the same speed?

# Impact of mass on orbital speed

Example question exploring how mass impacts orbital speed.

## Want to join the conversation?

• This initially made sense to me, but then I started to wonder about what if the mass of the satellite was extremely large? For example, let's say I want to put a satellite into the same orbit that is the same mass as the sun? Does the mass still truly not matter? If it were possible to put something the mass of the sun into the same orbit as the first satellite would it not cause the earth to fall straight into that satellite? Therefore, meaning that the mass of the second satellite does matter?
• You make a good point, but that equation is that of an object with mass m that is orbiting another object of mass M. In the scenario you described, you are completely correct to say that if the object with mass m had more mass than the object with mass M it would no longer be orbiting the other object. In the case that you described, the object that had the mass of the sun would have mass M, because it would no longer be orbiting the Earth, the Earth would have mass m and would be orbiting it. I apologize for the 7 month-long wait to get your question answered.
Hope this helps!
-Hyrum
• During the derivation of the formula, at the point where Sal equates the centripetal force, gravity, with (m)(a), why is m the mass of the smaller object? How do we know it's not referring to the mass of earth?
• I guess the capital M is to show the mass of the object that is getting orbitted around (e.g earth), while the lowercase m is the mass of the object that is in the orbit (e.g satellite)
(1 vote)
• If there is gravity in earth how does the earth's core stay in place