Physics 12 - Quiz 3

Sphere of Fear

Hiding behind every amazing feat is a great application of physics. Many circus performances include something known as the Sphere of Fear, or Circle of Doom, or the Globe of Death. The basic design consists of a metal cage in the shape of a sphere that is big enough to allow a motorcycle or two to ride around inside. If the rider goes fast enough they can even ride upside-down or around the side of the sphere without falling On Sunday, July 2, 2000, before a packed-to-capacity crowd, "Bela Tabak's Riders of the Thunderdome" accomplished the incredible: five motorcycles racing at 65 km/h within a 4.5 m diameter cage of metal mesh!

a) Given that the mass of the motorcycle and rider is 150 kg, find the force exerted by the steel cage on the motorcycle at the top and bottom of the cage. (4 marks)

b) What would be the minimum speed required at the top of the cage to successfully complete the loop. (3 marks)

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