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Topic: Jig Saw Puzzle
Replies: 2   Last Post: Jan 13, 1995 4:35 PM

 Messages: [ Previous | Next ]
 Evelyn Sander Posts: 187 Registered: 12/3/04
Jig Saw Puzzle
Posted: Jan 3, 1995 3:24 PM

Jig Saw Puzzle

Bolt a metal rod to the end of the blade of a jig saw so that the rod
can pivot in one plane. Here is a sketch of the object:

-------------
| ^^^^^^^^^^_|_______________________
| _________________________|
| ___________|
--------------
moves <---> pivots in the plane of the picture

In the picture the rod and blade are facing to the right. However,
notice that with the motor off, since the rod can pivot, if it is not
held in this position, it will fall and point downward.

What would you expect to happen if with the motor running you point
the object so that the rod and the blade face directly upward? Will
the rod fall to point downward? Will it continue to point upward
direction? Or will it instead point at some angle from the vertical?
Consider the case in which the length of the rod is much larger than
the gravitational acceleration over the square of the frequency of the

This puzzle is by no means easy. However, since it is not too hard to
visualize what is happening physically, I wanted to give people a
chance to at least think about the situation before I say what happens
and why. I will post an answer in a few days. Please do not post an answer
until then.

Date Subject Author
1/3/95 Evelyn Sander
1/9/95 Evelyn Sander
1/13/95 Evelyn Sander