Thrill of Zero G's: What Happens When You Reach 2.5 G's?

[Beachbum]

Amusement park rides, espically roller coasters, atract thousands for their ability to let people experience "zero veritcal g's" at the top of the hill. But how is it that if you have over 2.5 lateral g's in a turn of a coaster, you could die? Does your brain really compress against one side of your skull?

 

[zoobyshoe]

Amusement park rides, espically roller coasters, atract thousands for their ability to let people experience "zero veritcal g's" at the top of the hill. But how is it that if you have over 2.5 lateral g's in a turn of a coaster, you could die? Does your brain really compress against one side of your skull?

Where did you get this figure about 2.5 lateral g's causing death? If it's true there could be a lot of reasons why it would be so that don't necessarily involve the brain being compressed. What happens has to be affected by how quickly the 2.5 g's are applied, and probably how long they are applied for.

 

[rcgldr]

Few coaster's hit you with lateral g forces, generally they bank over so the g forces are relatively downwards, running up to 5 g's on some coasters. Some coasters do hit you with lateral g forces, like the typical carnival mouse right which does a lot of 180's at the tops. When they sped up the cars at the Matterhorn in Disneyland, the once coordianted banked turns now include some lateral force.

It's probably the moving platform rides that generate the most lateral forces, I don't know what the g forces are, but there have been a few deaths, on these, at least one girl died on the Disney Star Wars moving platform ride. I don't know if there have been any incidents with the Indiana Jones ride, but it's pretty violent as well. I would assume these are neck related injuries.

 

[russ_watters]

Plus, in a roller coaster, your head is generally not fixed in place, so lateral g's become vertical g's anyway unless you have disturbingly strong neck muscles.

Besides, Formula 1 drivers experience up to 3.5 lateral g's and their heads are fixed in place: http://www.formula1.com/insight/technicalinfo/11/468.html

Typically, a fighter pilot can handle 9 positive and 4 negative vertical g's (for a few seconds) and up to 12 positive for a very short time with a g-suit. Above that results in unconsciousness, but death can only come via oxygen deprivation and takes more g's for longer. Negative g's above 5 or 6 may cause blood vessels in the brain to rupture (not sure about how much it really takes), causing death.

 

[russ_watters]

Few coaster's hit you with lateral g forces, generally they bank...

That's my impression as well. Doing lateral g's throws in some additional mechanical and structural engineering challenges that probably aren't worth the effort.

 

[DaveC426913]

The body is already deisgned to deal with strong G's (including impacts) along its vertical axis. Not so with other axes.

Lateral G's have two undesirable effects that vertical G's do not:
1] the risk of banging one's head on the side of the coaster
2] the risk of neck injury from whiplash