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BransonMO
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I am trying to compare an experiment on spinal changes due to zero-g in astronauts. Researchers simulated zero-g spinal elongation by suspending human subjects so that no part of their body touched the ground.
This figure shows the % change in disc thickness for each subject compared to data obtained from astronauts in space.
I am trying to determine what is the best explanation for the significant difference in the spinal changes between the two groups:
1 - The mass of the volunteers did not decrease as it does in microgravity
2 - The weight of the body in the lab is still acting on the cartilage
3 - Volunteers were not suspended upside down to account for fluid accumulation in the head and neck
4 - Gravitational force is converted to tension in microgravity
Fnet = ma
[/B]
I think the best explanation is that suspension does not eliminate gravity, so there will be stretching forces at all places where the subjects were attached to suspension wires. This would cause an even greater elongation of the spine than just the absence of gravity, since now I have a tension (T) opposing the weight of the subject on their spine, and the net force will cause the tissue to deform.
Would this be as simple as Fnet = ma = T - mg?
so T = ma + mg = m (a+g) which is greater then the stretching force on spine that occurs simply by the lack of gravity in space. Howver, the net a on the body being suspended is 0, so that T = mg. I know that the lack of gravity is not the same as applying an opposing force (T) to the spine, but I am having a tough time using equations to prove it.
Is there a better way to calculate this, or to explain it?
This figure shows the % change in disc thickness for each subject compared to data obtained from astronauts in space.
I am trying to determine what is the best explanation for the significant difference in the spinal changes between the two groups:
1 - The mass of the volunteers did not decrease as it does in microgravity
2 - The weight of the body in the lab is still acting on the cartilage
3 - Volunteers were not suspended upside down to account for fluid accumulation in the head and neck
4 - Gravitational force is converted to tension in microgravity
Homework Equations
Fnet = ma
The Attempt at a Solution
[/B]
I think the best explanation is that suspension does not eliminate gravity, so there will be stretching forces at all places where the subjects were attached to suspension wires. This would cause an even greater elongation of the spine than just the absence of gravity, since now I have a tension (T) opposing the weight of the subject on their spine, and the net force will cause the tissue to deform.
Would this be as simple as Fnet = ma = T - mg?
so T = ma + mg = m (a+g) which is greater then the stretching force on spine that occurs simply by the lack of gravity in space. Howver, the net a on the body being suspended is 0, so that T = mg. I know that the lack of gravity is not the same as applying an opposing force (T) to the spine, but I am having a tough time using equations to prove it.
Is there a better way to calculate this, or to explain it?