Can someone explain G Forces with respect to roller coasters?

Question

I kept hearing that all day yesterday at cedar point. Are they talking about the pull on your stomach?

Answer 1

G Force is Gravitational Force- the effect of gravity on you.  A good roller coaster is going to pull around 4 G's.  It's enough force to give that pull on your stomach, but not damage your body.  

So yes, they are referring to that stomach feeling, and how much effect gravity has on your body during acceleration.

http://en.wikipedia.org/wiki/G_force

This website has some more technical, yet good explanations of it.  The Human experience section relates to roller coasters.

Answer 2

G Force is gravitational force. The amount of gravity on you when you ride. This is what makes roller coasters so much fun.

Positive vertical G's are when are forced down into your seat like when you go up a steep slope or while getting whipped around a loop at high speed.

Negative vertical G's are when you are forced up out of your seat and get "airtime". Negative vertical G's are found while going down a slope.

Lateral G's are when you are forced from side to side like on turns. There is no negative or positive because it is simply left and right.

Front G's (for lack of a better word) are when you are forced forward away from your seat when the car sharply stops.

Back G's (also for lack of a better word) are when you are forced backwards toward your seat when the car is boosted forward like on Top Thrill Dragster.

...yes that is the pull on your stomach.