Trying to understand orbiting objects in space

[mgsullivan24]

TL;DR Summary

I could really use help understanding stuff

I will try to hide how unintelligent and uneducated I actually am but I’m sure it’ll be showing throughout this question. My apologies. I really don’t know how else to find answers to questions I have besides coming to you all.

In a nutshell, I’m trying to understand why an astronaut floats inside the space station or a shuttle.
Google told me that at 200 miles out the effects of earths gravity are still at about 90%. I can understand “constant fall” idea from the balance of gravity and centripetal force. That would let the astronaut match the vessel in what I would call the horizontal movement.
But what about on the vertical axis. Why aren’t the astronaut and the vessel trying to orbit at different altitudes since their weight is so different? Why isn’t the astronaut being pulled to the ceiling or floor?

Thanks

 

[phinds]

Google "free fall".

Orbital mechanics dictates that an object that is moving TANGENTIAL to the Earth falls towards Earth but because it is also moving tangentially, the composite motion is a circle or ellipse around the Earth. While doing this the whole thing is weightless because it is in "free fall" which mean that it is freely falling towards Earth but again, because of the tangential component, it doesn't actually fall to Earth, it just moves weightlessly. Everything in it or on it is of course, also weightless.

 

[mgsullivan24]

Google "free fall".

Orbital mechanics dictates that an object that is moving TANGENTIAL to the Earth falls towards Earth but because it is also moving tangentially, the composite motion is a circle or ellipse around the Earth. While doing this the whole thing is weightless because it is in "free fall" which mean that it is freely falling towards Earth but again, because of the tangential component, it doesn't actually fall to Earth, it just moves weightlessly. Everything in it or on it is of course, also weightless.

Thank you for the reply. I have looked at that and it does make sense for the “weightlessness” of an object in orbit. Maybe I’m not understanding the correlation though. Why don’t the two objects try to move differently since the weights/mass are so different?

 

[Dale]

Why don’t the two objects try to move differently since the weights/mass are so different?

That is the way that gravity works. The force of gravity is proportional to the mass: $F=mg$. And Newton’s 2nd law is: $F=ma$. Combining those equations you get that $a=g$, regardless of $m$. So everything in free fall accelerates the same.

 

[PeroK]

Thank you for the reply. I have looked at that and it does make sense for the “weightlessness” of an object in orbit. Maybe I’m not understanding the correlation though. Why don’t the two objects try to move differently since the weights/mass are so different?

Here's an experiment to show that, once you remove air resistance, all objects have the same acceleration under the Earth's gravity. This experiment was famously carried out on the Moon by the Apollo 15 astronauts - the Moon has no atmosphere.



In general, this guy's videos are a good source for basic experimental physics.

This principle extends so that different objects will stay in the same orbit if they start in the same orbit.