Many of our internal organs hang down from our upper body - they give
us queasy sensations when they 'float upwards' in a negative 'G' situation
.HEAD GAMES
Physiological Effects/Psychological Effects
Your heart is racing, your stomach is churning and your knees are buckling under you. Just looking at that first drop is enough to inspire terror. Roller coasters are exciting, thrilling, entertaining, yet their sole purpose is to scare the poop out of you. The fear of the ride is enough to raise your pulse right up to 150 beats per minute as the adrenaline speeds through your veins.
Even before the roller ride begins, the stomach has already started to secrete extra acid, courtesy of the fight-or-flight response (which, in the case of roller coaster riders like me, is also known as the fight-flight-and-openly-weep response). When the coaster is actually underway, the increase in G-forces causes the stomach to flatten out. This sudden squashing can lead to the surprise reappearance of the chili dog and fries you ate only half an hour earlier and, in extreme cases, of every morsel of food you've consumed since roughly the mid-1990s.
Also affected by roller coaster motion are the semicircular canals in your inner ear and the bursas sacs that surround all the joints in your skeleton. When you move your head or body even a little bit, fluid in the canals and bursas sloshes against tens of thousands of tiny nerve endings, sending signals to your brain that tell it which way is up, which way is down, and so on. In a violently moving vehicle, the fluid splashes around so erratically that the nerve endings get confused, sending signals that they don't know which way is up, that they frankly don't care, and that if the brain thinks it's ever going to talk the rest of the body into getting on a roller coaster again, it's got another thing coming.
Many of our internal organs hang down from our upper body - they give
us queasy sensations when they 'float upwards' in a negative 'G' situation
.
So what is happening to our coaster rider during a negative G situation? It all depends upon the presence or absence of lap bars or other seat restraints. If the restraint is loose or absent then the rider has become a projectile in free fall - he stays out of contact with the seat because the car is locked to a track which is literally being pulled from underneath him.
If we have a high negative G situation for the car and no restraint then the rider free falls well out of his seat and will tend to hit the seat in front of him or may even leave the car altogether. Of course a coaster is not designed to be as severe as this though a foolish rider who manages to stand up takes a grave (literally) risk of being thrown out.
If the lap bar is fitted but 'loose' above the thighs then the rider
may rise an inch or two from the seat before contacting the bar - risking
some bruising in the process if it's not well padded. The lap bar then constrains
the rider providing the force needed to keep him in travelling 'with the
car' until the G force decreases and he falls back into his seat.
The riders will feel heavier at the bottom of a dip - they experience a force greater than their normal weight - typically up to a maximum value of 4 G's.
Fright Train, Last Car
You've accelerated many times before in your life, in fact, whenever you've been in a car that started up from a stop. As the car's rate of speed changed, the back of your seat pushed against you. The push made you accelerate also, but you would never stand in a long line just to accelerate in a car.
So what's the big deal about accelerating in a roller coaster? What is it about the ride that tells you that you are about to die? That within seconds, you will be thrown from your seat and splattered in a bloody mess on the ground? It's the rapidly increasing push from your seat (as opposed to the constant push from a car seat).
If you want to feel acceleration at its most terrifying, sit in the last
car of the coaster. Remember, as more cars go over the edge, acceleration
increases. By the time you go over, the push from your seat will be so great
that you'll feel like you're being thrown over the edge.
A high speed coaster does not necessarily produce a better ride than a low speed 'twister'. Our bodies are relatively insensitive to speed as such - we are much more responsive to acceleration and fluctuations of acceleration ('jerk'). Airline passengers may be flying at a steady 500 mph. but experience littleÝsensation of this when confined to a mid-row seat in the main cabin - we rely so much on peripheral vision for our sense of absolute speed so robbed of this our brains cannot interpolate the speed at which we are travelling.