I'm trying to figure out how to make a tire swing and a teeter-totter operate in my municipal park.
Try the tortoise machine side ways, or a disk & crank on a slow motor.
Remember those oscillating store displays, back in the '60s?
A magnetic coil given a timed pulsed to operate a pendulum.
Bob Schwartz
Thank you - I'll see what I can do with the ideas. I can sure pulse a solenoid and put a strong magnet in the tire - if I can find one small enough.
Bob
Consider putting a small magnet in the tire, and another magnet directly below the tire in the layout, with the poles opposing. The tire, on a very thin thread, will then oscillate around the opposing magnet, like swinging, and will require no power, etc. There is a desktop novelty sold in many stores that use the same principle.
Tom
Good idea Tom. I may have to give it a "kick" once in a while to start motion but I can handle that. I will try it. Lots of magnets in my scrap box. Bob
Another thought, the coil could go inside the tire. Just have it near a magnetic metal wall, e.g. steel. You only need a small pulse at the end of each swing, in order to keep the momentum going. BOB2
I can see this working, but not looking good. The reason would be that we have
an expectation for how long a pendulum takes to make an oscillation, and we
know that it's based on its length. So if you have a 3-inch pendulum bouncing
away, it's going to scream "TOY!" at the viewer.
But suppose the tire swung on a thin rigid wire. The point from which the
"rope" hung would be concealed fromn the viewer (by higher foliage, say) and
what you'd do would be to extend the wire past the pivot, and put another
weight ABOVE it. By manipulating the relative weights and lengths, you could
get a realistic swing time out of the model.
Also, suppose the magnet in the ground were slightly offset from a point
directly below the one in the tire, and suppose it were an electromagnet
instead of a permanent one (or it could be up in the tree instead of in the
ground). Then every few minutes you'd energize it briefly, so the tire would be
pulled towards it. After the power was cut off, you'd see the tire start to
swing and then gradually lose its speed. You could even hit it several times at
the tire's natural frequency, so as to build up momentum--a joy and a delight
for physics nerds of all ages!
John
Hmmm... Automating a brief pulse of a second or so every minute or
two would be easy. This one goes in the "to do" file.
Make the middle pivot point out of solid wire formed in an exaggerated U shape, which a piece of pipe placed in the middle to which the board on the see-saw is attached. The pipe will allow the board of the see-saw to move freely about the pivot point.
Get two figures which will be sitting on either end of the board.
For one figure, drill out the body cavity, leave empty and glue to the board. Drilling out of this figure is done to make it lighter.
For the other figure, drill out it's body cavity and fill part of it with something heavy. Then in the 'seat' of this figure, put a small chip from a magnet into the figure. Now the tricky part. This small piece of a magnet has to be 'the same polarity' as one of the Kadee electromagnets for uncoupling cars when it is energized. If a chip from a magnet won't fit in the 'seat' then consider mounting it behind the figure as sort of a back rest for the figure to lean against while riding. If done as a backstop, an equivalent made of something lightweight would need to be put behind the other figure as well to make it 'look right'.
Then bury the Kadee electromagnet underneath the end of the see-saw with the figure having the 'chip in their pants'.
When it you want the see-saw to move, energize the Kadee electromagnet which will make that figure move up. This due to magnets of the same polarity repulsing each other. Then when you want, de-energize the Kadee electromagnet and due to the extra weight in this figure and the lighter figure on the other end, gravity should return the figure to the ground/lower position. Might even do the prototypical 'bounce' upon hitting the ground!
You could put a third person straddling the pivot pipe 'going along for the ride'...
Don't forget adding in the 'T' handle made from pipe in front of the figures on the ends so they can hold on, if they want to.
Should end up with the typical see-saw motion with no cams, strings or wires showing which should have folks watching it scratching their collective chins wondering how you did this... ;)
I leave to others, where in this sequence to paint different parts prior to assembling.
Paul
Great idea, Thanks! Your suggestion makes a lot of sense and should be implementable.
An alternative might be to use a tiny air jet that is pulsed to cause the heavy end of the board to rise up momentarily. One of the DelAire gadgets might work.
Bob Schwartz