Virtual Capstan

[Mark Davidson]

Force is static.  Work is not static.  Work=energy=force*distance.
My concern is conservation of energy.
How do you get more work/energy out of the back of the key than you put in
at the front?
(Hint: you don't.)
Where does the extra work come from?

I understand the leverage issues/argument.  But leverage isn't energy.

-Mark



> At 12:09 PM -0400 6/21/03, Mark Davidson wrote:
> >This was my initial reaction.  You do less work at the front
> >of the key but the same amount at the back of the key.  How's that
possible?
> >Yet he's got the experimental data to show it works.
>
> Bill Ballard wrote:
>
> The data you refer to is static, and is merely a reading of how the
> gravitational pull on each side of the key is balanced across the
> fulcrum.
>
> >I think the answer lies in that fact that the magnets, like a spring,
have
> >stored energy that is released as the wippen and key move apart
> >which does some of the
> >work. This energy is stored again as the parts move back together.
> >It wouldn't
> >work if the distance between the parts were not changing.
>
> I don't know how it works for magnets, but for springs, barely 8% of
> of stored force is relieved at the top of the wippen's swing. The way
> to release 100% of the stored energy is to unhook the spring. With
> magnets, the force doesn't exist (excuse me, it doesn't become strong
> enough to be noticeable) until you bring like poles of two magnetic
> fields close enough. That doesn't sound like a force-storing system
> to me. Stored energy is at work however with inertia and gravity, as
> well as deformation of springs.
>