Have you ever wondered how roller coasters stay on their tracks
and why people can hang upside down in them? It’s all a matter
of physics: energy, inertia, and gravity.
A roller coaster does not have an engine to generate energy. The
climb up the first hill is accomplished by a lift or cable that
pulls the train up. This builds up a supply of “potential
energy” that will be used to go down the hill as the train
is pulled by gravity. Then, all of that stored energy is released
as “kinetic energy” which is what will get the train
to go up the next hill. So, as the train travels up and down hills,
its motion is constantly shifting between potential and kinetic
The higher the hill the coaster is coming down, the more kinetic
energy is available to “push” the cars up the next
hill, and the faster the train will go. Plus, according to Newton’s
First Law of Motion, “an
object in motion tends to stay in motion, unless another force acts
against it.” Wind resistance or the wheels along the track
are forces that work to slow down the train. So toward the end of
the ride, the hills tend to be lower because the coaster has less
energy to get up them.
The two major types of roller coasters are
wooden and steel. Features in the wheel design prevent the cars
from flipping off the track. Wooden tracks are more inflexible
so usually don’t have such complex loops that might flip passengers
upside down. In the 1950s tubular steel tracks were introduced. The
train’s nylon or polyurethane wheels run along the top, bottom,
and side of the tube, securing the train to the track while it
travels through intricate loops and twists.
When you go around a turn, you feel pushed against the outside
of the car. This force is “centripetal force” and helps
keep you in your seat.
In the loop-the-loop upside down design, it’s inertia that
keeps you in your seat. Inertia is the force that presses your
body to the outside of the loop as the train spins around. Although
gravity is pulling you toward the earth, at the very top the acceleration
force is stronger than gravity and is pulling upwards, thus counteracting
gravity. The loop however must be elliptical, rather than a perfect
circle, otherwise the centripetal (g) force would be too strong
for safety and comfort.
How do we know whether a roller coaster is safe? Engineers and
designers follow industry standards and guidelines. The first “riders” are
sandbags or dummies. Then engineers and park workers get to try
it out. Would you want to be one of the first passengers on a new
- Fun facts:
The “ancestor” of the roller coaster is traced
to Russia in the 15th century, a gravity sled ride called Russian
- One of the first roller coasters was in France in 1817 - Les
Montagnes Russes à Belleville (Russian Mountains of Belleville)
- the train axle was attached to the track by way of a carved
- In 1827, the Mauch Chunk Switchback Railroad, (Summit
Hill, PA) built
a track 18 miles down a mountain to transport coal. In 1873,
it became a scenic, albeit bumpy, pleasure ride. It remained
in operation until
- La Marcus Thompson built the Switchback Railway at Coney
Island, Brooklyn, NY, in 1884. He has been called the “father
of gravity” and
holds several patents including US Patent 310,966 (1885) for “Roller
coaster structure,” and US Patent 1,102,821 (1914) for “Signaling
device for racing coasters.”
- One of the first “high-speed” coasters was Drop-The-Dip,
at Coney Island, Brooklyn, NY (1907). At this time lap restraints
started to be used.
- The first tubular steel coaster was the Matterhorn Bobsleds at Disneyland, Anaheim, CA (1959).
- Knott's Berry Farm, Buena
Park, CA, introduced the Corkscrew (1975), the first coaster
to completely invert passengers.
- King Cobra, Kings Island, Cincinnati,
OH (1984) was the first roller coaster that allowed people to
- The longest roller coaster at this time is Steel Dragon
2000, Nagashima Spa Land, Japan, at 8,133 feet/2,479 m.
- As of
2005, the tallest steel continuous circuit roller roaster is
Kingda Ka at Six Flags Great Adventure, Jackson Township, NJ,
139m/456 feet. It is also the fastest at 128 mph/206 km/h. A ride lasts
Dana. Sign, space, and story: roller coasters and the
evolution of a thrill. Journal of popular culture,
v. 33, Fall 1999: 1-22.
Louis A. How everything works: making physics out
of the ordinary. Hoboken, NJ: Wiley, c2007. 720 p.
Robert. The incredible scream machine: a history
of the roller coaster. Fairview Park, OH, Amusement Park Books;
Bowling Green, OH, Bowling Green State University Popular
Press, c1987. 252 p.
Joe, and others. Amusement park rides and brain injuries. Injury
prevention, v. 9, March 2003: 6.
Julie. The big thrill, the hidden danger. Prevention,
v. 54, July 2002: 40.
Jenny. How extreme can roller coasters go? Three new
rides raise the bar again, and there's no end in sight.
Popular science, v. 262, Apr. 2003: 26-27.
Hilary, Steve Mills, and Korey T. Kiepert. Using
math to design a roller coaster. Milwaukee, WI, Gareth Stevens
Pub., 2007. 32 p. (Juvenile literature)
Paul. Roller coaster! Chicago, Raintree, c2007. 32 p.
Paul. Scared to death. Popular mechanics, v. 180, Aug.
Scott. The American roller coaster. Osceola, WI, MBI
Pub. Co., 2000. 160 p.
rides may be heartfelt. Harvard health letter, v. 31,
June 2006: 6.
Todd H. Roller coasters: United States and Canada. 2nd
ed. Jefferson, NC, McFarland, 2000. 303 p.
more print resources...
Search on "Roller
coasters," "Roller coasters—Design and function," "Amusement
rides" or "Amusement parks"
in the Library of Congress Online
"Hold on to your hat!" Prints & Photographs
Division, Library of Congress (scanned from print.)
Loop the loop,
Luna Park, Coney Island, [between 1903 and 1910]
Looping the loop,
Atlantic City, 1901. Prints & Photographs Division, Library
Cyclone at Coney Island has been terrorizing riders since the late
1920s." Photo from the USGS
Field Trips to the Shore Web page.
Giant Dipper, a National Historic Landmark, at Santa Cruz, CA. Photo from the National Park Service Web site.
Photo from the Recreation
Facility Guidelines page, United States Access Board Web
is just one of the many roller coasters that add a twist to physics
lessons. Credit: Geauga Lake & Wildwater
Kingdom. From the NASA Life on Earth Web site.