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Re: Loaded dice



Howdy-

I have thrown weighted dice. They seem to work.

I suspect that it isn't on the way down, but when it hits that's the key.
When it is sitting on an edge, the side with the greater torque will
probably win, and that side is the weighted side. I say probably because the
rotational speed might be too high for the torque to keep it from rolling.

The second reason -- although I suspect it is less important -- is that when
a die is falling through the air with the weighted side horizontally, the
weighted side is likely to rotate downwards.

X -------- o
^ ^

X = weighted side, o = fair side

Same upwards force on both, but the weighted side has a greater force of
gravity downwards, therefore the net torque is counter-clockwise in my
picture.

-----

I am told that a psychic once claimed to be able to affect the outcome of a
six-sided die. Over 1000 rolls, the number of 6's was in fact slightly
higher than expected.

The psychic wasn't able to get any other number to roll higher though,
leading to suspicion. Apparently, it turned out that the 1 is heavier (fewer
pips removed) than the 6 and is located on the opposite side of the 1.

I am told that this is why casinos use die where the pips are painted on
rather than dug out.

------

It is easy to detect a weighted die. Spin the die like a dreydel (a top) on
two axes. It is pretty easy to do after you've practiced a few times. A
weighted die precesses badly.


------

Shaving sides works, too, but it can also be detected. Stack the dice.
Switch the orientations, stack again. Repeat. If the dice are square, the
heights should be the same every time.


Marc "Zeke" Kossover







-----Original Message-----
From: Bob Sciamanda [mailto:trebor@VELOCITY.NET]
Sent: Monday, December 02, 2002 3:17 PM
To: PHYS-L@lists.nau.edu
Subject: Re: Loaded dice

You read my consternation correctly, John. Since all masses experience
the same acceleration in a gravitational field, there must be some other
reason for the heavier side to out-run the others. With most objects I
would look for differences in air resistance, because of shape. Not
applicable here. I am left with a vague appeal to a tumbling phenomenon
and am trying to remember applicable dteails of past studies of "rigid
body motion". The "tennis racket theorem" (only the words) just came to
mind! Please elucidate!
-Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor
----- Original Message -----
From: "John Mallinckrodt" <ajm@CSUPOMONA.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, December 02, 2002 3:56 PM
Subject: Re: Loaded dice


| >Is it true that a dice is "loaded" by adding an internal weight near a
| >given face. Is this supposed to favor the dice falling with this face
| >"down"? Someone please explain(???)
|
| This would seem to me to be the case and it probably doesn't hurt if
| the dice are of the "rounded edge" variety. See, for instance,
|
| http://www.halfpast.demon.co.uk/dd.html
|
| But why do I think you must have some sort of a theory to suggest
| that this shouldn't work? ;-)
|
| --
| John Mallinckrodt mailto:ajm@csupomona.edu
| Cal Poly Pomona http://www.csupomona.edu/~ajm