Why did the Wilberforce pendulum swing?
I beg your pardon, but my pendulum doesn't swing! (See the real answer below.)
5.) Why does the pendulum stop, turn, and then bounce up and down?
If you have a slinky handy, try this: hold the two ends of the slinky, one in each hand. Leave five or six coils between your fingers and pull the slinky slightly open. Can you feel it twisting? The coils of a slinky, as they bounce in and out do two things. One is they bounce, the other is they twist. When they are bouncing, they are producing a strong twisting force, and when they twist they produce a bouncing force. The result is that they go back and forth between just bouncing and just twisting.
I am really glad you didn't ask me how the slinky remembers what it was doing last when it is exactly in between bouncing and twisting. I don't know the answer to that. Maybe it has to do with the way the slinky spirals and the direction the weight is turning. I'll have to watch more carefully next time!
6.) What is the pendulum used for?
The Wilberforce Pendulum is useful for teaching students about physics and not much else. On the other hand, a scientist here at the lab told me that NASA once launched a satellite that had springy antennas (so they could fold up for launch) and when it got into orbit it acted in a very confusing way, and wouldn't stay aimed straight. They figured out that the antennas were bouncing around like the Wilberforce pendulum and upsetting the satellite.
