Re: Angular momentum

If i had to guess, i would say that the tip accelarates as a consequance of:

A: force provided by the jerk backwords to "snap" the whip/fly.

B: I can picture it as being simolar to an angular rotation problem with th
body rotating at one end. For example, placing a uniform rod with a pivot at
one end, hanging from a ceeling. As a result of the angular motion when the
system is released, the tip of the rod will accelerate faster than gravity.
But the whip is not ridgid like a rod, and it is not simply under the
influance of gravity. Also, the segments of the whip do not accelerate
uniformly, this causes the whip to retard in such a way the the tip falls
behind the midpoint in the whips trajectory (this is when tall towers begind
to fall, they break apart). As the segments of the whip begin to reach full
extension (starting near the hilt of the whip), the whips radius of rotation
becomes smaller and smaller, and finally at the tip, when the radius is at
its smallest, the energy reaches a maximum, and then the signature "snap"
when the tip inverts and collides with itself.



"Repeating Decimal" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> in article [EMAIL PROTECTED], Richard at
[EMAIL PROTECTED]
> wrote on 10/25/03 5:05 PM:
>
> >
> >
> > Timtro wrote:
> >>
> >> I'm sorry to bother you all with this question. I was just playing
around
> >> with a problem I found in a book. It is a simple problem where in a man
sits
> >> on a stoll free to ratate without friction and is spun around while he
holds
> >> two 3kg weights. we are given the moment of inertia of the man+stool,
> >> initial speed and the fact that the weights are 1m from the axis of
> >> rotation. The man then contracts his arms to 0.3m from the axis of
rotation.
> >> Obviously the man will go faster because of this, but when I calculated
the
> >> initial and final kinetic energies, they were VERY differant. Where did
all
> >> that extra energy come from? Or did I calculate the energy wrong?
> >
> > The man had to do work to reel in the weights.
>
> One of my pet interests is fly fishing and the cazsting required to   put
a
> fly out where you want it to go. The process is similar to that used in a
> whip.
>
> A heavy line, ususally tapered in thickness, is flicked out using arm
> motion. After the flick (cast) is completed, arm motion ceases. The line
> continues to travel. The speed of the tip can increast (in the case of a
> whip) close to the speed of sound. Often, the whip cracks or a fly gets
> flicked of the leader.
>
> How does the tip get speeded up? Aside from incidental losses to sound and
> the like, is mechanical energy conserved? Is momentum conserved? If not,
> where does extra momentum com from?
>
> If there is a discussion on the subject here, and if no one figures it out
> (an unlikely situation) I will reveal the mechanisms in a week or two.
>
> Bill
>