Will 'artificial gravity' based on centrifugal force really work?
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In an answer to another question of mine, concerning gravity, there was a link to a video about creation of artificial gravity, based on rotation.
The question I have might be silly (or with an obvious answer), but it puzzles me non the less. As I understand it, in order for the centrifugal force (which is responsible for creating gravity, in this case) to work, object it works upon should be attached to the wheels 'spoke' or 'rim'. If an astronaut walks on the inside of the 'rim' (like here in the video), the contact with the 'rim' is maintained via legs, thus centrifugal force is in action.
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
newtonian-mechanics forces reference-frames free-body-diagram centrifugal-force
edited 8 hours ago
Qmechanic♦
100k121811133
asked 8 hours ago
Filipp W.
1764
add a comment |
up vote
6
down vote
favorite
In an answer to another question of mine, concerning gravity, there was a link to a video about creation of artificial gravity, based on rotation.
The question I have might be silly (or with an obvious answer), but it puzzles me non the less. As I understand it, in order for the centrifugal force (which is responsible for creating gravity, in this case) to work, object it works upon should be attached to the wheels 'spoke' or 'rim'. If an astronaut walks on the inside of the 'rim' (like here in the video), the contact with the 'rim' is maintained via legs, thus centrifugal force is in action.
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
newtonian-mechanics forces reference-frames free-body-diagram centrifugal-force
edited 8 hours ago
Qmechanic♦
100k121811133
asked 8 hours ago
Filipp W.
1764
3
For an experimental exploration of answers to this question, take three friends and a dodgeball to your nearest playground with a merry-go-round. Get the merry-go-round up to speed, then have the folks who are riding it try to play "catch" with the dodgeball. Take turns observing from off the merry-go-round to see the difference between the rotating frame and the inertial frame. What happens is quite surprising, even if you make a prediction on paper beforehand, because the intuition you use to play "catch" is not well-adapted to rotating reference frames.
– rob♦
6 hours ago
What you could worry about is the effect of tidal force. Even for a big wheel the variation of acceleration, $a=omega r$, is non negligible. You head will weigh less when standing up then when lying down.
– my2cts
6 hours ago
Technically yes, they will experience zero gravity at some point during their jump, but not because of the natural lower gravity of space. Instead, it will be because your acceleration upwards is temporarily 0, suspending you in mid-air before the centrifugal force is greater and begins to pull you back down (the initial rotational acceleration).
– Anoplexian
3 hours ago
It seems to work just fine. Space Station Centrifuge Gravity Simulation 196x NASA color 3min The word jump needs to be in the title.
– Mazura
2 hours ago
1
While jumping may remove you from the force imparted by the "floor" of the rotating drum, consider that you have momentum and will continue to move. The direction of this movement will be tangent to the curve of the rotating drum in the direction of rotation. So while you will not "fall" straight back down to the floor, you will drift forwards with your current momentum and... bump right back into the floor.
– Blackhawk
1 hour ago
add a comment |
up vote
6
down vote
favorite
up vote
6
down vote
favorite
In an answer to another question of mine, concerning gravity, there was a link to a video about creation of artificial gravity, based on rotation.
The question I have might be silly (or with an obvious answer), but it puzzles me non the less. As I understand it, in order for the centrifugal force (which is responsible for creating gravity, in this case) to work, object it works upon should be attached to the wheels 'spoke' or 'rim'. If an astronaut walks on the inside of the 'rim' (like here in the video), the contact with the 'rim' is maintained via legs, thus centrifugal force is in action.
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
newtonian-mechanics forces reference-frames free-body-diagram centrifugal-force
edited 8 hours ago
Qmechanic♦
100k121811133
asked 8 hours ago
Filipp W.
1764
In an answer to another question of mine, concerning gravity, there was a link to a video about creation of artificial gravity, based on rotation.
The question I have might be silly (or with an obvious answer), but it puzzles me non the less. As I understand it, in order for the centrifugal force (which is responsible for creating gravity, in this case) to work, object it works upon should be attached to the wheels 'spoke' or 'rim'. If an astronaut walks on the inside of the 'rim' (like here in the video), the contact with the 'rim' is maintained via legs, thus centrifugal force is in action.
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
newtonian-mechanics forces reference-frames free-body-diagram centrifugal-force
newtonian-mechanics forces reference-frames free-body-diagram centrifugal-force
edited 8 hours ago
Qmechanic♦
100k121811133
asked 8 hours ago
Filipp W.
1764
edited 8 hours ago
Qmechanic♦
100k121811133
asked 8 hours ago
Filipp W.
1764
edited 8 hours ago
Qmechanic♦
100k121811133
edited 8 hours ago
Qmechanic♦
100k121811133
edited 8 hours ago
Qmechanic♦
100k121811133
100k121811133
asked 8 hours ago
Filipp W.
1764
asked 8 hours ago
Filipp W.
1764
asked 8 hours ago
Filipp W.
1764
1764
3
For an experimental exploration of answers to this question, take three friends and a dodgeball to your nearest playground with a merry-go-round. Get the merry-go-round up to speed, then have the folks who are riding it try to play "catch" with the dodgeball. Take turns observing from off the merry-go-round to see the difference between the rotating frame and the inertial frame. What happens is quite surprising, even if you make a prediction on paper beforehand, because the intuition you use to play "catch" is not well-adapted to rotating reference frames.
– rob♦
6 hours ago
What you could worry about is the effect of tidal force. Even for a big wheel the variation of acceleration, $a=omega r$, is non negligible. You head will weigh less when standing up then when lying down.
– my2cts
6 hours ago
Technically yes, they will experience zero gravity at some point during their jump, but not because of the natural lower gravity of space. Instead, it will be because your acceleration upwards is temporarily 0, suspending you in mid-air before the centrifugal force is greater and begins to pull you back down (the initial rotational acceleration).
– Anoplexian
3 hours ago
It seems to work just fine. Space Station Centrifuge Gravity Simulation 196x NASA color 3min The word jump needs to be in the title.
– Mazura
2 hours ago
1
While jumping may remove you from the force imparted by the "floor" of the rotating drum, consider that you have momentum and will continue to move. The direction of this movement will be tangent to the curve of the rotating drum in the direction of rotation. So while you will not "fall" straight back down to the floor, you will drift forwards with your current momentum and... bump right back into the floor.
– Blackhawk
1 hour ago
add a comment |
3
For an experimental exploration of answers to this question, take three friends and a dodgeball to your nearest playground with a merry-go-round. Get the merry-go-round up to speed, then have the folks who are riding it try to play "catch" with the dodgeball. Take turns observing from off the merry-go-round to see the difference between the rotating frame and the inertial frame. What happens is quite surprising, even if you make a prediction on paper beforehand, because the intuition you use to play "catch" is not well-adapted to rotating reference frames.
– rob♦
6 hours ago
What you could worry about is the effect of tidal force. Even for a big wheel the variation of acceleration, $a=omega r$, is non negligible. You head will weigh less when standing up then when lying down.
– my2cts
6 hours ago
Technically yes, they will experience zero gravity at some point during their jump, but not because of the natural lower gravity of space. Instead, it will be because your acceleration upwards is temporarily 0, suspending you in mid-air before the centrifugal force is greater and begins to pull you back down (the initial rotational acceleration).
– Anoplexian
3 hours ago
It seems to work just fine. Space Station Centrifuge Gravity Simulation 196x NASA color 3min The word jump needs to be in the title.
– Mazura
2 hours ago
1
While jumping may remove you from the force imparted by the "floor" of the rotating drum, consider that you have momentum and will continue to move. The direction of this movement will be tangent to the curve of the rotating drum in the direction of rotation. So while you will not "fall" straight back down to the floor, you will drift forwards with your current momentum and... bump right back into the floor.
– Blackhawk
1 hour ago
3
3
For an experimental exploration of answers to this question, take three friends and a dodgeball to your nearest playground with a merry-go-round. Get the merry-go-round up to speed, then have the folks who are riding it try to play "catch" with the dodgeball. Take turns observing from off the merry-go-round to see the difference between the rotating frame and the inertial frame. What happens is quite surprising, even if you make a prediction on paper beforehand, because the intuition you use to play "catch" is not well-adapted to rotating reference frames.
– rob♦
6 hours ago
For an experimental exploration of answers to this question, take three friends and a dodgeball to your nearest playground with a merry-go-round. Get the merry-go-round up to speed, then have the folks who are riding it try to play "catch" with the dodgeball. Take turns observing from off the merry-go-round to see the difference between the rotating frame and the inertial frame. What happens is quite surprising, even if you make a prediction on paper beforehand, because the intuition you use to play "catch" is not well-adapted to rotating reference frames.
– rob♦
6 hours ago
What you could worry about is the effect of tidal force. Even for a big wheel the variation of acceleration, $a=omega r$, is non negligible. You head will weigh less when standing up then when lying down.
– my2cts
6 hours ago
What you could worry about is the effect of tidal force. Even for a big wheel the variation of acceleration, $a=omega r$, is non negligible. You head will weigh less when standing up then when lying down.
– my2cts
6 hours ago
Technically yes, they will experience zero gravity at some point during their jump, but not because of the natural lower gravity of space. Instead, it will be because your acceleration upwards is temporarily 0, suspending you in mid-air before the centrifugal force is greater and begins to pull you back down (the initial rotational acceleration).
– Anoplexian
3 hours ago
Technically yes, they will experience zero gravity at some point during their jump, but not because of the natural lower gravity of space. Instead, it will be because your acceleration upwards is temporarily 0, suspending you in mid-air before the centrifugal force is greater and begins to pull you back down (the initial rotational acceleration).
– Anoplexian
3 hours ago
It seems to work just fine. Space Station Centrifuge Gravity Simulation 196x NASA color 3min The word jump needs to be in the title.
– Mazura
2 hours ago
It seems to work just fine. Space Station Centrifuge Gravity Simulation 196x NASA color 3min The word jump needs to be in the title.
– Mazura
2 hours ago
1
1
While jumping may remove you from the force imparted by the "floor" of the rotating drum, consider that you have momentum and will continue to move. The direction of this movement will be tangent to the curve of the rotating drum in the direction of rotation. So while you will not "fall" straight back down to the floor, you will drift forwards with your current momentum and... bump right back into the floor.
– Blackhawk
1 hour ago
While jumping may remove you from the force imparted by the "floor" of the rotating drum, consider that you have momentum and will continue to move. The direction of this movement will be tangent to the curve of the rotating drum in the direction of rotation. So while you will not "fall" straight back down to the floor, you will drift forwards with your current momentum and... bump right back into the floor.
– Blackhawk
1 hour ago
add a comment |
2 Answers
2
active
oldest
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up vote
11
down vote
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
Well, here's a related question. Suppose you find yourself in an elevator at the top floor of a skyscraper when the cable suddenly snaps. As the elevator plummets down, you realize you'll die on impact when it reaches the bottom. But then you think, what if I jump just before that happens? When you jump, you're moving up, not down, so there won't be any impact at all!
The mistake here is the same as the one you're made above. When you jump in the elevator, you indeed start moving upward relative to the elevator, but you're still moving at a tremendous speed downward relative to the ground, which is what matters.
Similarly, when you are at the rim of a large rotating space station, you have a large velocity relative to somebody standing still at the center. When you jump, it's true that you're going up relative to the piece of ground you jumped from, but you still have that huge rotational velocity. You don't lose it just by losing contact with the ground, so nothing about the story changes.
answered 8 hours ago
knzhou
39.6k9110193
1
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
3
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
add a comment |
up vote
5
down vote
If you jump then you are in free fall, apart from air resistance, so you are weightless. This holds for any jump. For a brief moment you experience zero gravity!
answered 7 hours ago
my2cts
4,0392416
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
11
down vote
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
Well, here's a related question. Suppose you find yourself in an elevator at the top floor of a skyscraper when the cable suddenly snaps. As the elevator plummets down, you realize you'll die on impact when it reaches the bottom. But then you think, what if I jump just before that happens? When you jump, you're moving up, not down, so there won't be any impact at all!
The mistake here is the same as the one you're made above. When you jump in the elevator, you indeed start moving upward relative to the elevator, but you're still moving at a tremendous speed downward relative to the ground, which is what matters.
Similarly, when you are at the rim of a large rotating space station, you have a large velocity relative to somebody standing still at the center. When you jump, it's true that you're going up relative to the piece of ground you jumped from, but you still have that huge rotational velocity. You don't lose it just by losing contact with the ground, so nothing about the story changes.
answered 8 hours ago
knzhou
39.6k9110193
1
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
3
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
add a comment |
up vote
11
down vote
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
Well, here's a related question. Suppose you find yourself in an elevator at the top floor of a skyscraper when the cable suddenly snaps. As the elevator plummets down, you realize you'll die on impact when it reaches the bottom. But then you think, what if I jump just before that happens? When you jump, you're moving up, not down, so there won't be any impact at all!
The mistake here is the same as the one you're made above. When you jump in the elevator, you indeed start moving upward relative to the elevator, but you're still moving at a tremendous speed downward relative to the ground, which is what matters.
Similarly, when you are at the rim of a large rotating space station, you have a large velocity relative to somebody standing still at the center. When you jump, it's true that you're going up relative to the piece of ground you jumped from, but you still have that huge rotational velocity. You don't lose it just by losing contact with the ground, so nothing about the story changes.
answered 8 hours ago
knzhou
39.6k9110193
1
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
3
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
add a comment |
up vote
11
down vote
up vote
11
down vote
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
Well, here's a related question. Suppose you find yourself in an elevator at the top floor of a skyscraper when the cable suddenly snaps. As the elevator plummets down, you realize you'll die on impact when it reaches the bottom. But then you think, what if I jump just before that happens? When you jump, you're moving up, not down, so there won't be any impact at all!
The mistake here is the same as the one you're made above. When you jump in the elevator, you indeed start moving upward relative to the elevator, but you're still moving at a tremendous speed downward relative to the ground, which is what matters.
Similarly, when you are at the rim of a large rotating space station, you have a large velocity relative to somebody standing still at the center. When you jump, it's true that you're going up relative to the piece of ground you jumped from, but you still have that huge rotational velocity. You don't lose it just by losing contact with the ground, so nothing about the story changes.
answered 8 hours ago
knzhou
39.6k9110193
Now, the question: if, while being inside a rotating space station, astronaut would jump really high, wouldn't he then experience zero gravity until he again will touch some part (wall or floor) of the station? Am I missing something in my understanding?
Well, here's a related question. Suppose you find yourself in an elevator at the top floor of a skyscraper when the cable suddenly snaps. As the elevator plummets down, you realize you'll die on impact when it reaches the bottom. But then you think, what if I jump just before that happens? When you jump, you're moving up, not down, so there won't be any impact at all!
The mistake here is the same as the one you're made above. When you jump in the elevator, you indeed start moving upward relative to the elevator, but you're still moving at a tremendous speed downward relative to the ground, which is what matters.
Similarly, when you are at the rim of a large rotating space station, you have a large velocity relative to somebody standing still at the center. When you jump, it's true that you're going up relative to the piece of ground you jumped from, but you still have that huge rotational velocity. You don't lose it just by losing contact with the ground, so nothing about the story changes.
answered 8 hours ago
knzhou
39.6k9110193
answered 8 hours ago
knzhou
39.6k9110193
answered 8 hours ago
knzhou
39.6k9110193
answered 8 hours ago
knzhou
39.6k9110193
39.6k9110193
1
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
3
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
add a comment |
1
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
3
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
1
1
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Another, related example: A hovering helicopter on earth does not see the earth move underneath it with 1000 km/h or so (due to earth rotation), simply because that same helicopter was moving at the same speed with the earth all along.
– user1583209
8 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
Please do correct me if I am wrong, but I think here what happens in your explanation is that although you do land on the same spot of the disc after jumping off, it’s less due to the efffect of gravity and more due to the ring rotating to ‘catch’ you. Although you do have a horizontal velocity, when you jump off I think you don’t actually move in a circle, rather you move in a straight line until hitting the ring again. In that sense, OP is technically correct since you aren’t really(assumed gravity negligible) under the effect of some centrifugal force when you jump?
– EigenFunction
7 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
@EigenFunction You definitely are under such a force in the rotating frame of reference of the rim of the station. True, an external observer would see you move in a straight line and intersect the rim again with no centrifugal force involved, but that observer never sees a centrifugal force--only the centripetal normal force of the station's rim on your feet.
– eyeballfrog
6 hours ago
3
3
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
@EigenFunction You could always say that, though. For example, you could say that gravity on Earth doesn't really exist: a thrown ball always goes in a straight line, but the floor is just constantly accelerating up to catch it. The fact that this is always just as good a description is the content of the equivalence principle, i.e. the foundation of general relativity. You just can't tell the two apart.
– knzhou
5 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
If you enter the spinning room from the center axle, you would just float there, though? And if the astronaut jumps really high, why don't they land on their head or side when the ring rotates to meet them?
– simpleuser
2 hours ago
add a comment |
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If you jump then you are in free fall, apart from air resistance, so you are weightless. This holds for any jump. For a brief moment you experience zero gravity!
answered 7 hours ago
my2cts
4,0392416
add a comment |
up vote
5
down vote
If you jump then you are in free fall, apart from air resistance, so you are weightless. This holds for any jump. For a brief moment you experience zero gravity!
answered 7 hours ago
my2cts
4,0392416
add a comment |
up vote
5
down vote
up vote
5
down vote
If you jump then you are in free fall, apart from air resistance, so you are weightless. This holds for any jump. For a brief moment you experience zero gravity!
answered 7 hours ago
my2cts
4,0392416
If you jump then you are in free fall, apart from air resistance, so you are weightless. This holds for any jump. For a brief moment you experience zero gravity!
answered 7 hours ago
my2cts
4,0392416
answered 7 hours ago
my2cts
4,0392416
answered 7 hours ago
my2cts
4,0392416
answered 7 hours ago
my2cts
4,0392416
4,0392416
add a comment |
add a comment |
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3
For an experimental exploration of answers to this question, take three friends and a dodgeball to your nearest playground with a merry-go-round. Get the merry-go-round up to speed, then have the folks who are riding it try to play "catch" with the dodgeball. Take turns observing from off the merry-go-round to see the difference between the rotating frame and the inertial frame. What happens is quite surprising, even if you make a prediction on paper beforehand, because the intuition you use to play "catch" is not well-adapted to rotating reference frames.
– rob♦
6 hours ago
What you could worry about is the effect of tidal force. Even for a big wheel the variation of acceleration, $a=omega r$, is non negligible. You head will weigh less when standing up then when lying down.
– my2cts
6 hours ago
Technically yes, they will experience zero gravity at some point during their jump, but not because of the natural lower gravity of space. Instead, it will be because your acceleration upwards is temporarily 0, suspending you in mid-air before the centrifugal force is greater and begins to pull you back down (the initial rotational acceleration).
– Anoplexian
3 hours ago
It seems to work just fine. Space Station Centrifuge Gravity Simulation 196x NASA color 3min The word jump needs to be in the title.
– Mazura
2 hours ago
1
While jumping may remove you from the force imparted by the "floor" of the rotating drum, consider that you have momentum and will continue to move. The direction of this movement will be tangent to the curve of the rotating drum in the direction of rotation. So while you will not "fall" straight back down to the floor, you will drift forwards with your current momentum and... bump right back into the floor.
– Blackhawk
1 hour ago