Question dealing with Newton's Laws of Motion?

Question

Each of the vertebrae forming your spine is separated from its neighbors by disks of eleastic tissue. What happens, then, when you jump heavily on your feet from an elevated position? Why are you a little taller in the morning than you are at the end of the day?

Answer 1

Jumping from an elevated position can compress the spinal discs due to the pressure. It could cause injury to some people.

When you are horizontal, laying on your back, you are generally a little longer than you are tall when standing.

The flexible cartilage discs between the spinal vertebrae compress slightly downward due to your weight while standing making you a little shorter than when reclining.

Also as you age, these cartilage discs may shrink slightly over the years and cause you to get slightly shorter in your elder years than you were as a younger adult. This is why your elderly grandfather may be a little shorter than he was when he was a young man.

Even astronauts are taller in space than on earth because there is no gravity compressing their spinal discs.


"The effects of gravity on the" upright human posture are powerful: Individuals are as much as 25 mm taller in the morning than in the evening, as a result of compressive forces bearing down all day, and astronauts 'grow' by nearly 75 mm when released from the force of the earth's gravity".

Quoted from:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1459276
 

Answer 2

The fact that your spine elongates when gravity is not pressing in a downward direction is evident not only when one wakes up in the morning, but very evident in persons exposed to microgravity. Part of every astronaut's day in space in excercise designed to try and compress the spine since there is no gravity to do this. If they did not do these ecercises, their spines would stretch and curve to make them hunch over forward. Astronauts who have been in space for very extended periods of time are actually a bit taller than when they left and it takes awhile for them to return to their normal height.

Answer 3

Hi. That's two questions but the discs are slightly compressible. In the morning (actually after laying down for hours) they "decompress" and add a bit to your height. You can check this easily. The jump will cause the discs to compress for a second and absorb the impact.

Answer 4

Homework question. You ought to be ashamed.

Here's my answer; I didn't research this, but it goes with a bit of cognitive/deductive reasoning and a little bit of common sense:

At the point you "gather yourself" just before jumping upward, the force you exert on yourself down to gather as much potential energy as you can before jumping is used to "squish" the bones of your vertebrae just slightly. At the point just before you jump, the most force is exerted, and for a split second, acceleration downward (from the force you exerted) is zero, and you're at the max value of potential energy for yourself.

The release of this elastic potential energy (elastic meaning there's some tension involved) in the form of kinetic (motion) energy then happens in the act of jumping. Energy is shot upward vertically from your feet (the point at which you gathered most of your potential energy to begin with) to your head, which allows for a thrust upward from the ground. You temporarily overcome the force of gravity, disconnecting yourself only momentarily from the Earth's surface.

All the while, the Earth continues to pull you downward, and your velocity into the air decreases to zero (at the same instant you reach your max height). Gravity overcomes your upward thrust once all potential energy has turned to kinetic to bring you to your point in the air. At that point, the kinetic energy which caused you to move in the air turns to potential (PE = mgh, where "h" is your height from the ground), then back to kinetic as you fall back down.

Oh, and to answer your last question:
People are generally taller in the morning because they've been on their feet the least amount of time at this point in the day. Gravity exerts a constant force downward on our bodies, and while we're standing upright, that force has a noticeble affect on our vertebrae, which eventually squishes it with time. By the end of the day, we're shorter because there's less space measured between each of the vertebrae do to this squishing.

Answer 5

Did you even try answering this yourself?

Answer 6

Hmmm... So you expect me to do YOUR homework?