- #1
chirumu
- 7
- 0
Homework Statement
i measured myself before going to sleep and after waking up over several nights and found out I'm ~1.5cm taller in the morning then at night. I know this question is related to human biology, but I'm equally (if not more so) interested in the physics behind the problem i.e. how gravity affects the body.
Homework Equations
The Attempt at a Solution
I understand that cartilage in the body has an elastic / flexible / resilient nature and that gravity causes compression of cartilage in the spinal cord / knees. Gravity on Earth does not change, so the body is exposed to the same force of gravity regardless of wether one is standing or lying down: why then does this difference in height occur?
I'm going to take into account hydrostatic pressure because the body is 60% fluid. So, pressure = F / area. Gravity acts in one direction (downwards) so if you change the surface area for gravity to act on then pressure exerted on the body changes accordingly, i.e. if you lay down at night you increase your surface area for which gravity can act on, pressure on the body decreases and the cartilage of the body is able to expand again.
i feel like there should be more to it. I'm curious if there's anything else to consider here or if I'm completely thrown off :S