User talk:Ifsteelman

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Coriolis
Hi Ifsteelman,

I saw you had added a comment on the Talk:Coriolis effect page.

The current version of the coriolis effect article is contradicting itself badly, as a consequence of edits by disagreeing contributors.

The animations in the article are manufactured by me. I am currently working on a version that is aimed at merging the various inputs, but with inner consistency, and of course, featuring solid newtonian dynamics. Work-in-progress-version of the coriolis effect article

I would like to you read it, and please do not jump to conclusions, there is more to rotational dynamics than meets the eye. Please give yoursel ample time to reflect on it. Rotational dynamics is really cool newtonian physics --Cleon Teunissen | Talk 10:42, 11 August 2005 (UTC)

Angular momentum and rotational kinetic energy

 * 2. the first definition of the Coriolis force given in the article is what we call here conservation of momentum: if a ice-skater stretches her arms or pulls them to her body while rotating on herself, her speed will change. Kinetic energy and momentum will be conserved. We don't connect this here to a Coriolis effect. --Ifsteelman 06:57, 11 August 2005 (UTC)

Hi Ifsteelman,

It is tempting to assume that momentum and kinetic energy change in synchrony, but that is not the case.

The moment of inertia is given by $$ I = m r^2 $$  The angular momentum is given by $$ L = I \omega $$  The rotational kinetic energy is given by $$ E_r = \frac{1}{2} I \omega^2 $$

Let the radius of circular motion be contracted with a factor of $$\sqrt(2)$$  That means a reduction of the moment of inertia with a factor of 2. That means an increase of angular velocity by a factor of 2

The rotational kinetic energy is proportional to the moment of inertia, and proportional to the square of the angular velocity. The moment of inertia is halved, the angular velocity is twice as high, so in contracting there has been een increase of the rotational kinetic energy with a factor of 2.

In order to contract a rotating system work must be done, increasing the rotational kinetic energy. If you don't pump in that extra kinetic energy you are not going to get any contraction.

So in contracting and relaxing rotational motion, with just a radial force, there is no conservation of rotational kinetic energy. There is conservation of angular momentum, but no conservation of rotational energy.--Cleon Teunissen | Talk 13:36, 11 August 2005 (UTC)