 |
Teaching
Guide |
This teaching guide is
designed to complement the 20-minute video, Go Figure. Click here to request
the video. Please note that video supplies are limited and may no longer be
available.
Flying Carpets on Wheels:
Fun and Physics with Roller Coasters
What is it about roller coasters that provokes someone to stand in
line for three hours just to ride one? Some think it has to do with "Fight or
Flight" syndrome. When a person gets scared, the pancreas produces large amounts of
adrenaline that helps face fears instead of fleeing. While waiting in line, the body
produces adrenaline. After the ride, an excess of adrenaline produces an "adrenaline
rush." That's why some people notice they have an abundance of energy after stepping
off a roller coaster.
That people will actually pay to be scared was evident as far back as the 1400s when
the earliest roller coasters were developed in Russia. Carts made of ice rode on ice
slides built of wood or sometimes built into mountains. Some slides were 70 feet high.
Large holes chiseled into the ice carts were filled with straw and used as seats. People
climbed long sets of stairs to the top for a quick ride to the bottom.
Soon these large slides began appearing in other countries with warmer climates, only
the ice and straw were replaced with wood and steel. Many of these rides were constructed
in France in the 1700s and were called Les Montagnes Russe, which means Russian Mountains.
The first roller coaster-type ride in America didn't appear until the 1800s when a
passenger car was added to an old gravity-powered mine train. Soon the train was a
full-time attraction. Mules pulled the carts up the hill and paying customers rode the
carts to the bottom, reaching six miles per hour.
It's All Physics
Through the years, roller coasters evolved. Designers added more twists, turns, drops, and
even loops. Yet there's one thing all coasters have in common: a fundamental basis on the
principles of physics.
Aside from clothoid loops, the roller coaster is basically a simple machine, and can be
easily thought of in terms of kinetic and potential energy. The coaster's lift motor
exerts enough energy to lift the carts to the top of the hill, increasing their potential
(stored) energy (PE). As the first cart reaches the peak, its PE is converted to kinetic
energy (KE), the energy of motion. The process is repeated for each cart. KE increases
as the coaster travels down the hill. But when it reaches the bottom and starts to climb
the next hill, KE is again converted to PE.
Gee! G Forces!
Another important concept in roller coaster physics is g (gravity) forces. As the cart
goes up and down and makes sharp turns, the passengers' bodies feel the same forces that
astronauts feel while traveling into space. These forces are recorded by accelerometers
and calibrated in g's. When standing on earth, people normally experience the sensation of
1 g of acceleration vertically, which equals an acceleration of 9.8 m/s2. A g force of 3
gives a person the sensation of being three times heavier than normal weight.
During a roller coaster ride, different positions cause different g forces. Positive g
forces, which give the sensation of a weight increase, are experienced during ascent.
Negative g forces are experienced during descent and give the sensation of a weight
decrease.
When in free fall (falling with the force of gravity as the only influence) the
coaster seat is exerting no force on the passenger. In this instance, the person
experiences 0 g's and the sensation of weightlessness.
Inertia
G forces also can be exerted laterally or from side to side. When the coaster goes
through a curve, the passengers' bodies want to keep going forward; thus, they are pinned
to the side of the coaster. This can be illustrated by the principle of inertia .
Roller coaster designers can convert lateral g forces into positive g's by
"banking a turn." If the carts are tilted inward while going through a curve,
the floor, rather than the side of the cart exerts a force on the passenger.
Clothoid Loop
The days of simple roller coasters with a few small hills are long gone. Today's coasters
are bigger and scarier than ever, many having loops. Early-day looping coasters had
circular loops. At the top of the loop the carts began to slow down and at the end of the
loop they were going too fast. The development of the clothoid loop solved this problem.
By decreasing the loop's radius at the top, the speed is increased enough to keep
passengers pressed into their seats. At the same time, the radius at the bottom of the
loop is increased so that the curve isn't sharp enough to hurt people. The result is a
loop that is more elliptical than circular.
Safe?
Speaking of loops often brings up the subject of roller coaster safety. The sight of a
body dangling hundreds of feet in the air leads to the question, "How safe are roller
coasters?"
Roller coaster designers say, "Safe enough." They have the task of
manipulating g forces just enough to make the ride feel dangerous while using these same
forces to keep passengers safely on the coaster.
Sources
Pescovitz, David. "Roller Coasters: Inventing the Scream
Machine." Encyclopedia Britannica, Inc. 1998. Online. Netscape.
Physics Day. Six Flags St. Louis Theme Parks, Inc. The Amusement Park
Physics Committee of The St. Louis Area Physics Teachers Association. 1997 Six Flags Theme
Parks, Inc.
Snyder, Dr. Stephanie, Michael Hartman, and Victoria Roxo. "The P’s
and K’s of Energy." June 1998. Online. Netscape.
Wayne, Tony. "Roller Coaster Physics." Online. Netscape. 28 July 1998.
Video Game U. | Up in the Air | Flying Carpets | What's the Password?
Saw Me a Tune | Guess What? | Classroom Activities
Last Updated: 02/16/03
This Web site made possible by ConocoPhillips.
Copyright 2003
ConocoPhillips. All rights reserved.
For more information or to send comments, please send an e-mail to teach@conocophillips.com.
|
