Why do astronauts feel weightless inside a space ship and centrifugal force?

[scilearner]

Hello everyone,

 

 

Ok so I read that the reason they are in free fall is because they are going in a circle like this , and the earth curves away from them at the same time or something, could anyone explain it to me simply. Also why don't astraunauts get pushed to the periphery of the space ship by the centrifugal force?They are not wearing belts right, do they I don't know? Thanks

[Ophiolite]

You need to abandon the diagram you have used. It is not exactly relevant to your question.

You have the heart of the matter in your statement "the earth curves away from them".

 

Let's take it back a little further with a thought experiment. Imagine you are at the top of a tower, beyond the Earth's atmosphere. You throw a ball so that its initial flight is parallel to the Earth's surface. The ball moves forward in the direction you have thrown it, but it also falls downward because of gravity. Eventually it hits the surface of the Earth.

 

Now through the ball faster. Again it falls in a curve, but this time it gets further from the tower before it hits the Earth. Instead of throwing the ball fire it out of a powerful cannon. If you make it move fast enough it will move forward just as far as it moves down, so that its curve will match the curvature of the Earth. It is now falling around the Earth.

 

The spaceship is falling around the Earth. Its occupants are falling around the Earth. Both are falling at the same rate.

 

Does this help, or have I just confused you?

[swansont]

There is no centrifugal force acting on them; if you draw a FBD in an inertial frame, it will not appear.

 

The feel weightless because they are in perpetual freefall, with the centripetal force being the gravitational force. When we "feel gravity" we are actually feeling the other forces that are counteracting it. In a circular orbit, there are no other forces to feel.

[Mr Skeptic]

They feel nothing because all parts of them and their spaceship are being accelerated by exactly the same amount. You only feel a force if different parts of you are being accelerated to different degrees and your internal body forces are acting to make up at least some of the difference. For example when standing, your leg bones and muscles counteract the gravitational pull on your head, the skin under your feet is under some pressure, etc.

 

(Not entirely true as there are a few bumps on earth and earth's gravitational field that can be measured by specialized and very sensitive probes)

[J.C.MacSwell]

Hello everyone,

 

 

Ok so I read that the reason they are in free fall is because they are going in a circle like this , and the earth curves away from them at the same time or something, could anyone explain it to me simply. Also why don't astraunauts get pushed to the periphery of the space ship by the centrifugal force?They are not wearing belts right, do they I don't know? Thanks

 

Just think about this for a second. Why does the space ship not get pushed up against the astronaut in his orbit? (Same reason as explained by the previous replies, they are in free fall together)

[scilearner]

Thanks for all the replies.They were all very helpful I understand now,this is not a string force, this is gravity and free fall occurs.