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True demonstrations of the Coriolis force are few and far between. One apparatus, constructed at the University of Washington, is pretty good. They took a cylinder a few feet wide, put it on a rotating turntable, and then poured concrete into it. Eventually the concrete set in a bowl-shaped pattern due to the centrifugal force. They then polished the surface and mounted a camera on top that spins with the cylinder. Objects released on the surface of the bowl of concrete experience deflections that are due entirely to the Coriolis force.
This is a whole lot more complicated than the traditional demonstrations that involve a turntable or a merry-go-round. But the trouble with the other demonstrations is that they are actually for the most part demonstrating the centrifugal force. In the Washington apparatus, the centrifugal force is everywhere normal to the surface of the concrete, so it doesn't affect the motion of any objects. The same with the Earth: the centrifugal force plus gravity are everywhere normal to the surface of the Earth, so only the Coriolis force alters the path of moving objects.
The traditional turntable or merry-go-round demo involves rolling a ball from the center of the turntable toward the edge and noting that it follows a curved path. But the Coriolis force isn't supposed to affect objects that are stationary. What happens if you are on a merry-go-round and simply release a ball? It flies off to the side, because of the centrifugal force. What happens if you are on a merry-go-round and toss a ball behind you, opposite the direction of motion of the merry-go-round? Does it curve inward toward the center, as the Coriolis Force would have you believe? No, it curves outward and flies off the edge of the merry-go-round, because of the Centrifugal Force. By picking an example in which the (usually stronger) centrifugal force acts in the same direction as the (usually weaker) coriolis force, science teachers around the world have been bamboozling students for generations.
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