On Mon, 30 Dec 1996, zeropoint <zap@dnai.com> wrote:
   parallel@bluesky.net.au (earthling) writes:
uuummm...don't flame me !  But any constructive criticism is always appreciated. This is my very first posting on the usenet.
  
  Has anyone ever noticed the similarities between the Lorentz Force and  the Magnus Effect ?    For those who have never heard of either term, a simple definition of  each follows :-    ---> The Lorentz Force is the centripetal force experienced by a  MOVING CHARGED particle as it travels through a magnetic field. Only  that component of the particle velocity at right angles to the field  is involved. The field does not add any energy to the particle  velocity. The field, the velocity, and the force are always at right  angles to each other, so as the direction of travel of the particle  changes the force also rotates accordingly. The particle ends up  travelling in a circle or a spiral path, depending on the angle at  which it enters the magnetic field. Loss of kinetic energy should also  be taken into consideration. For those who prefer an equation, here it  is..  F = Bq (V sinq), where B is the field strength, q is charge, V is  velocity, and q is the angle between the (total) velocity and the  field. If all of the particle velocity is at right angles to the  field, then sin90 = 1, means maximum force experienced by the  particle.
  
  ---> The Magnus Effect is the centripetal force experienced by a  MOVING SPINNING object as it travels through a fluid medium. (The  proviso is that the object be capable of dragging some of the  surrounding fluid around it's 'equator' as it spins - i.e. it needs to  have a rough surface...like a golf ball or a tennis ball). Only that  component of the object velocity at right angles to the spin axis is  involved. The rate of spin does not add any energy to the object  velocity. The spin axis, the velocity, and the force are always at  right angles to each other, so as the direction of travel of the  object changes the force also rotates accordingly. The object would  end up travelling a full circle if gravity and fluid fluctuations did  not act upon it. Golfers and tennis players use the Magnus Effect all  the time, when they use backspin or sidespin to good effect for their  game. Assuming a spinning golf ball travels through the air and drags  some of that air around its equator, it creates a slight vacuum on one  side (at the surface of the ball) where the air is hauled away from  the oncoming wind. On the opposite side, the fluid is thrown into the  oncoming wind and the pressure is increased. The net force on the ball  causes it to change direction continuously. The equation describing  the Magnus Effect is a little complicated for my liking...look it up  if you wish.
  
  Pretty damn similar I think and not just a coincidence ! I do have  more thoughts on the matter, but I wont waffle on unless I get a positive response or two (then try and stop me..hehe).