[Seany (OP)]

Why?

[Seany (OP)]

Curious with this one too.. Is it that our body is moving at such a great speed, that our intestines/guts are experiencing alot of pressure?

But what is wrong with that theory is that, we go at about 500km/hr in an aeroplane? And the speed of a roller coaster is only about 90mph..

Maybe it has something to do with vectors, and has to have a direction going down?

[another_someone]

It has nothing to do with speed, and everything to do with acceleration.

The major problem is usually not with the tummy, but with the inner ear, which is designed to detect balance (i.e. it knows which way is down by which way gravity is pulling on the liquid within the inner ear).  The trouble is that roller coasters cause all sorts of G forces in lots of different directions, so your ear gets confused about what is up and what is down.

Why this effects your tummy, I am not sure.

Some people I think have suggested that because your brain is confused, it thinks it has been poisoned, and so tries to make you sick in order to remove the poison from your system - I am not totally convinced about that argument, although I am not qualified to say it is wrong.

My own suspicion is maybe that the intestines use the force of gravity to help food go down, and when you are upside down (i.e. have negative G forces applied to your body), they try and compensate for this by trying to push food through by muscle power against the force of gravity.  When you are constantly being bounced around with G forces constantly changing, your intestines might simply get confused as to how much effort they should apply in order to keep the food moving at the right speed that it will spend the right amount of time in each part of the digestive process.  This is pure guesswork, and might be totally wrong.

Another possibility, somewhere between the two ideas above, might be that as the body experiences negative G, the stomach tries to close off to prevent digestive juices from flowing back the wrong way.  If the negative G is applied too quickly, the stomach and intestines cannot react quickly enough, and a small amount of gastic juices do flow back up.  This causes the intestines to think that their is some sort backpressure caused by a toxin or infection, and tries then to purge that toxin or infectious agent by regurgitating the food.

[Seany (OP)]

You mentioned about being upside down. But it isn't just for upside down. It's for when you go downhill really fast. Or go over a really lumpy hill on you car at fast speed. I think its mostly to do with the downward motion, but I'm not sure what is happening.

[another_someone]

You mentioned about being upside down. But it isn't just for upside down. It's for when you go downhill really fast. Or go over a really lumpy hill on you car at fast speed. I think its mostly to do with the downward motion, but I'm not sure what is happening.

Upside down can be detected by two different means, and the two will not always agree.

Your eyes can tell you which way is up, and which way is down.

Your ears can tell you which way gravity is pulling you.

If you are accelerating downwards faster than the pull of gravity, then your ears will tell you that you are being pulled towards your head rather than towards your feat, and so will believe that you are upside down (your intestines will also feel the same way).

While most roller coasters are simply pulled down by gravity, and so cannot accelerate downwards faster than gravity itself, nonetheless the rapid changes from strong downward force (as you have gravity pulling you down at the same time as you are also accelerating upwards) followed rapidly by zero G (as you go into freefall downwards), and then back to strong upwards force again, will all contribute to confusion about what is up and what is down, as the ears try and work out what is the average  force they are being subjected to.

[Seany (OP)]

Ah ok. I heard that the ears are the things which know how to balance your head. So if your head is tilted, you know because of your ears, or something around your eyes or within or whatever.

I think that poison theory makes quite sense, although it does sound more fictional. Except, since our bodies system works in a similar way, it might just think that we have been poisoned.

[another_someone]

If you want to know about the ultimate in roller coaster rides - look up about the vomit comet that the astronauts use for training.

[Seany (OP)]

Vomit comet? []