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Name:  Elizabeth R.
Status: educator
Age: 30s
Location: N/A
Country: N/A
Date: 2000-2001

What is the physics and the history of the "Giant Drop" at Six Flags Great America. It is a free fall ride. But how does it really work?

Dear Elizabeth,

This type of ride is known as a tower thrill ride or free fall. It is a rather simple ride that gives a huge thrill. Typically, there are six "cars" that carry four guest each, arranged around a 70 meter tower. There is a cabled hook that lifts each car to the top, and after about 10 seconds at the top, releases the cars for a plunge back to the ground.

Let us begin with the braking system. Strong magnets are mounted into the backs of each car. The bottom 40% or so of the tower has thick copper plates attached to the tower. As the magnets pass around the copper plates, they generate eddy currents. These currents in turn generate an opposing magnetic field, hindering movement of the car. These currents are broken up by occasional cuts in the copper strips. In this way, braking can be controlled.

There is a counterweight in the tower that assists in the ascent of the ride. The brakes work on the way up, also. Once beyond the copper strips, there is a burst of acceleration until the top is reached. After a short delay, the lift hook is released, allowing the car to free fall until the brakes. After the sharp braking, you are then gently returned to the ground.

Each car has a set of safety harnesses that are both lap and shoulder design. They must all be locked and checked, and a safety switch must be pressed for each car. After all are set, safety interlocks at the entrance and exit must also be depressed simultaneously with the operator to activate the ride.

---Nathan A. Unterman

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