On Feb 6, 2006, at 11:10 AM, Harry Veeder wrote:
I am interested in how gravimagnetic theory may pertain to the motion
of a curling stone.
When a curling stone is slowly rotating as well as sliding the path of
motion tends to "curl" in the direction of rotation. Why this happens
remains very controversial but each explanation advanced assumes
a unique model of the frictional forces involved.
Since gravimagentism is isomorphic with electromagnetism, then
then the appearance of a gravimagentic field depends on the relative
acceleration or deceleration of the masses.
In regards to a stationary Earth, the sliding motion (deceleration)
of a
curling stone over the Earth generates a relatively weak gravimagnetic
field. However if the curling stone is regarded as stationary and
the Earth
as sliding under the curling stone, then the deceleration of the
Earth will
generate a relatively intense gravimagnetic field.
Add a little rotation to the mix and I have a hunch that the "curl" of
curling stone can be explained by gravimagnetism.
What do you think?
Harry
I don't think gravimagnetism has anything to do with it. The
gravimagnetic forces involved here are way too small.
There are (at least) a couple existing theories. See:
<http://www.timesonline.co.uk/article/0,,2090-1325839,00.html>
On first glance, Shegelski's theory looks like it makes more sense
than Marmo's, but you can't discount practical knowledge. It seems
to me some fairly simple experiments could figure out the truth.
One reason Marmo's theory looks bad is that forces directed
longitudinally to the sides simply tend to make an object spin, not
laterally accelerate. There is no significant Bernoulli principle
involvement as there is with baseballs, etc.
My first impulse, having no practical experience with curling at all,
is to suggest the sheer force between the ice and the stone at the
back is greater than the similar sheer force at the front of the
stone. Thus a net right directing force exists on a moving and
clockwise turning stone. When the added ice and water burden is
brushed from the ice, the front end of the stone lowers, the water
surface width decreases, and the shear force increases.
Marmo states: "My theory is quite simple compared to theirs, which
doesn't explain why there is much more water at the front than the
back ?".
I would think a correct theory would tend to make use of this fact
more than explain it. The more water up front, the less the sheer
force of the water on the front of the stone. To increase the
leftward force on the front of the stone, and thus balance the
rightward force at the back, it is only necessary to reduce the
amount of water and meltable ice the stone runs over and thus drop
the front of the stone so it runs on a thinner layer of water. When
the front end of the stone rides on the same amount of water as the
back the shear forces are balanced and the stone goes straight.
That's my guess. Only good data can tell for sure.
Horace Heffner.
