Rock and roll thrills

The city will have at least two new roller coasters by 2012, offering new highs for thrill-seeking fun lovers, Hong Kong's two leading theme parks have announced.

Ocean Park's HK$5.55 billion makeover will include the construction of a floorless rollercoaster, the Hair Raiser. It will be 860 metres long, will reach speeds of 88km/h with a push of 4Gs - or four times normal gravity - making it the longest and fastest at the park.

The expansion will also include a bobsled-themed rollercoaster called Arctic Blast. It will be just under half the Hair Raiser's length, hitting speeds of 36km/h and pulling 2Gs, a spokeswoman said.

Disneyland will also have two new roller coasters completed before 2014, including a runaway-mine-train-style coaster in its new Grizzly Gulch Frontier Gold-Mining Town area and a U-shaped shuttle coaster in its Toy Story Land expansion, according to a spokesman.

Currently, local thrill seekers can choose from only three roller coasters in town, or nine of varying intensity in Shenzhen.

Ocean Park's oldest operating roller coaster, the 821-metre Dragon, built in 1984, has a top speed of 77km/h and is the longest outdoor rollercoaster in the city.

Disneyland's only rollercoaster, the enclosed Space Mountain, was opened in 2005 and runs some 1,051 metres. It features in-car speakers and special effects.

Sham Shui Po's Dragon Centre also has a steel-track roller coaster on its top floor, but it has been shut down indefinitely, according to the mall's management.

History

The Switchback Railway on Coney Island, New York, built in 1884, was designed by LaMarcus Adna Thompson who held the patent for a 'scenic gravity railroad'. But the first versions of the roller coaster were built in Russia on artificial hills of ice outside St Petersburg in the late 1700s.

Roller coasters became enormously popular in the United States until the Great Depression of the 1930s.

In 1959, Disneyland built its Matterhorn Bobsleds ride. But it was the construction of the Racer at King's Island in Cincinnati, Ohio, with a top speed of 98km/h, that revived the popularity of the roller coaster.

Roller coaster physics

According to physics professor Wang Jian of the University of Hong Kong, roller coasters are perfect examples of classical mechanics. Every roller coaster uses:

Potential energy

Kinetic energy

Gravity

Free-fall

Velocity

Projectile motion

Acceleration

Centripetal acceleration

Friction

Acceleration stress

Centrifugal force

For a crash course on the physics properties of roller coasters, try looking up some of the terms at search.eb.com/coasters/ride.html