Thrills without spills.Amusement-park rides are a scream. But are they safe? Ride designers invite you to use the laws of physics to find out. Abandon all hope," warns the sign above the spinning rotor ride at the Coney Island Coney Island (kō`nē), beach resort, amusement center, and neighborhood of S Brooklyn borough of New York City, SE N.Y., on the Atlantic Ocean. amusement park amusement park, a commercially operated park offering various forms of entertainment, such as arcade games, carousels, roller coasters, and performers, as well as food, drink, and souvenirs. in New York City New York City: see New York, city. New York City City (pop., 2000: 8,008,278), southeastern New York, at the mouth of the Hudson River. The largest city in the U.S. . But that didn't stop Lourdes Gonzalez, 24, and dozens of other thrill seekers Thrill Seekers was a television series aired in 1973 and 1974. It was hosted by Chuck Connors and featured people who did dangerous stunts. Other works Thrill Seekers (USA) / The Time Shifters from climbing aboard last July. At first, everything ran as scary - but as "normal" - as usual, Gonzalez says. She and the other passengers lined up along the inner rim of the barrel-like ride. The operator set the barrel spinning and the liders were "glued" to the wall. When the floor dropped out, they felt like they were flying. But suddenly - Kablam! - the passengers really were flying - out of the ride. The accident mangled Gonzalez's right leg; 12 other people suffered back injuries and bruises. What went wrong? Inspectors found that a huge metal strap, which held the barrel's wall panels together, suddenly snapped in two. "One of the panels struck the operator's booth and that portion of the barrel tore open," says Vahe Tiryakian, spokesperson for the New York City Department of Buildings, which inspects amusement-park rides. Without warning, the passengers were flung through the gaping hole (see diagram, left). That incident got me thinking: Just how safe are amusement-park rides? Could a speeding roller coaster What a bad CD-R disc is often called. See CD-R and underrun. go flying off the tracks? Could an accident like the rotor disaster happen again? SAFETY SCARE The answers depend largely on physics, says Ron Toomer Ronald Valentine Toomer (born 31 May 1930) is one of the prominent roller coaster designers in the world. He graduated from the University of Nevada with a degree in Mechanical Engineering. He was on the design team for the heat shield on the Apollo spacecraft. , a mechanical engineer who designs roller coasters While there have been hundreds of different roller coasters built, there have been just a few that were notable for specific reasons. Some reasons include:
When the barrel and floor start to spin, the people move too. At any given instant, the riders are moving sideways. And like all moving objects, they would keep moving in a straight line (sideways) if no other forces acted on them, Toomer says. That tendency to keep moving in one direction is called inertia. (Remember Newton's first law of motion Noun 1. Newton's first law of motion - a body remains at rest or in motion with a constant velocity unless acted upon by an external force first law of motion, Newton's first law ? See SW 9/1/95, p. 12.) But rotor riders can't keep moving in a straight line because the curved walls of the rotor get in the way. The riders "fly" into the wall and stay pinned - even when the floor drops. FICTIONAL FORCE For years, people thought an outward-pushing force, which they called centrifugal force centrifugal force Fictitious force, peculiar to circular motion, that is equal but opposite to the centripetal force that keeps a particle on a circular path (see centripetal acceleration). , was what kept rotor riders pinned to the wall. But believe it or not, Toomer says, centrifugal force doesn't exist. What's really happening, he explains, is that inertia makes the riders fly outward. They feel pressed to the wall by the force of the wall holding them in. The center-pushing force that holds them in is known as centripetal force Centripetal force The inward force required to keep a particle or an object moving in a circular path. It can be shown that a particle moving in a circular path has an acceleration toward the center of the circle along a radius. . At Coney Island, when "the rotor wall panel suddenly "disappeared," Toomer explains, the centripetal force disappeared too. With no force to hold the passengers in, they flew off the ride. The Coney Island rotor accident was probably the result of human oversight, Toomer says. (For example, someone may have missed a crack in the metal strap). But for most ride designers and inspectors, he says, "safety is the number-one priority." Look at a giant roller-coaster loop, for example. It's similar to a rotor turned on its side, says Toomer. On the loop, the "pushed-to-the-wall," feeling created by centripetal force helps keep people in their seats - even when the coaster cars turn upside down. Decades ago early roller-coaster designers tried to make perfectly circular loops. But they soon rejected that idea when they realized that gravity (Earth's downward pull) would slow the cars too much at the top of the loop. At such slow speeds, centripetal force would weaken to the point that gravity could pull riders to the round. Conversely, at the bottom of a circular loop, the riders would be moving so quickly that centripetal force would increase and squish squish v. squished, squish·ing, squish·es v.tr. To squeeze or crush together or into a flat mass; squash. v.intr. To emit the gurgling or sucking sound of soft mud being walked on. the riders in their seats uncomfortably. So instead, designers make teardrop-shaped roller-coaster loops (see photo.) This design tightens the curve at the top where the coaster train slows down. The tighter curve increases centripetal force, the force that keeps you pinned to your seat, Toomer says - so you don't fall out. At the bottom of the loop, where the train speeds up, centripetal force increases more. But because the curve is more stretched out, Toomer explains, you don't feel too squished. Many other innovations keep rides scary - but safe. These include wheels embedded inside tubular steel tracks (to help keep ride cars - and riders - on track), and cushioned, over-the-shoulder harnesses (to keep you buckled in). Designers also run the rides through dozens of trials before you ever climb on board. "It's always easy to find people who want to be the first to test a new coaster," Toomer says. And inspectors routinely examine ride machinery, in some cases using X-rays to check metal rides for cracks or other problems that you can't see on the surface. Because of the Coney Island rotor accident, New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of inspectors may soon require those tests. Still, with all these safety measures safety measures, n.pl actions (e.g., use of glasses, face masks) taken to protect patients and office personnel from such known hazards as particles and aerosols from high-speed rotary instruments, mercury vapor, radiation exposure, anesthetic and , accidents do happen. In 1994, an estimated 7,200 people were treated in hospital emergency rooms for minor injuries (mainly bumps and bruises) associated with amusement-park rides, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the U.S. Consumer Product Safety Commission. Though that number may seem high, says John Graff, executive director of the International Association of Amusement Parks and Attractions International Association of Amusement Parks and Attractions (IAAPA) [www.IAAPA.org] Founded in 1918, IAAPA is the largest international trade association for permanently situated amusement facilities worldwide. , you have to consider that 400 to 500 million people take billions of rides each year. "Most of the accidents occur because people are standing up, horsing around, or goofing off," he says. Kind of makes you wonder: Maybe riding too many amusement-park rides can scramble your brains. DESIGN A RIDE! The challenge: Design the "Fling & Float," a ride that combines the thrill of amusement-park rides, The setup: Riders sit in rafts attached to cords. A machine spins the rafts around a platform. At a certain point, each cord snaps and fling the rafting rider into a lagoon (see top-view diagram, below). The catch: At what point on the spinner (A-D A-D Advance-Decline, or measurement of the number of issues trading above their previous closing prices less the number trading below their previous closing prices over a particular period. ) should the cords detach de·tach v. 1. To separate or unfasten; disconnect. 2. To remove from association or union with something. so that riders land in the lagoon? This experiment may help you decide: WHAT YOU NEED: rubber ball * 1-m (3-ft.) piece of string * partner * masking tape WHAT TO DO: 1. Tie string securely around ball. 2. In an open area, hold the end of the string and swing the ball over your head, lasso lasso (lăs`ō, lăs  `), light, strong rope, usually with a smooth, hard finish, made of a fine quality of hemp or nylon. style. 3. Predict: Where will the ball fall if you release the string when your arm is directly in front of you? Have a friend record your prediction. 4. Stop swinging and release the string simultaneously. (Make sure classmates Classmates can refer to either:
5. Repeat Steps 2 through 4 three times. Then try different release positions. Notice any patterns? CONCLUSIONS At what point on the "Fling" ride should you release each ride? DON'T STOP NOW! How does centripetal force help make your ride a success? What safety measures would you add? RIDE WRECK: Disaster struck the spinning rotor ride at Coney Island, New York, last summer when passengers were flung from the ride. Here's what happened: 1 Riders entered the rotor through a door. 2 The operator closed the door and started the ride. 3 As the barrel spun at 97kph (60mph), riders felt pressed against the wall by centripetal force, the force holding them in. When the floor dropped 3m (10ft), riders felt like they were flying. 4 Suddenly, a metal strap holding the barrel together snapped. Part of the wall tore off. Without the inward push of centripetal force, riders flew off the ride - flung by their own inertia. Thirteen people were injured. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion