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how to make a swinging sticks kinetic structure? Answered

i have to make a physics project and i need it to be ready by the end of the year.i loved this structure in the iron man 2 movie,and want to surprise my friends and my teacher at school.help pleease!!!


Jack A Lopez

5 years ago

It's funny.  When I first saw this sculpture, I imagined the moving pieces to be a single T-shaped piece sort of twirling around the top of that lambda shaped base.  But that was just optical delusion on my part.

In reality this scupture is two moving pieces: two sticks.  The first stick is pinned to a bearing at the vertex of the lambda shaped base, and the second stick is pinned to a bearing on one side of the first stick.  So the motion of the sticks is pretty much confined to a 2D plane.  Essentially this sculpture is two pendulums stuck together, a.k.a. a "double pendulum"

I am guessing the way this sculpture is being pumped,  i.e supplied with energy, is via an electromagnet in the base which pushes-pulls a permanent magnet in the end of one of the sticks.

The same trick is used for powering those plastic solar-powered dancing animals, like those sold at the "dollar stores" in my home country, e.g.

If you have have one of those stores near you,  one of those solar dancing animals can supply some of the parts needed, specifically I am thinking of the electromagnet, which is typically this pancake-shaped coil made of a  huge number of turns of very fine magnet wire, and that part would be hard to find... if it was not sold in the package of a solar novelty dancing animal at a dollar store near you.

Also I want you to look at this PDF from Solarbotics(r)
which includes a circuit diagram for the the driving the sense/pump coil. 

There is actually something subtle going on with that.  Part of the time the coil is a sensor, waiting for the magnet to come near it.  Then the coil switches to being an actuator, to turn on and push the magnet away. The subtle part is how the electromagnet is able to "kick" the magnet at just the right time, so as to keep the motion going.


5 years ago

Hint: they aren't solid sticks, they are hollow tubes with a balancing weight hidden in one end.


5 years ago

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