Re: Swing and momentum

Martin Hogbin wrote:

"BernardZ" <bernardZ@xxxxxxxxxx> wrote in message news:MPG.1eed2e0942dec8e09899e2@xxxxxxx
While going on a child swing, I was trying to explain the mechanics.

What I found myself stuck on was the momentum. As the swinger goes
higher and higher, the swing velocity on the bottom gets faster and
faster so there does his angular momentum.

Since momentum is conserved where is the other side of the angular
momentum, the only think I can think is the air must be pushed away and
so preserving the angular momentum. Okay if so then a swing should not
work in a vacuum. Which does not sound right!

Angular momentum is not conserved for a swing.

Next you'll be telling me it violates the 2nd Law of Thermodynamics.

It's amazing how children can pump swings, while drawing a force
diagram explaining how they do it might challenge bright freshman
physicists. Of course the Earth and gravity are the other side of the
equation for conserving angular momentum, just as for a pendulum. But
I've never gone through the exercise of understanding how it is
possible for a person dangling in the seat to pump it up in the first
place.

Swings don't seem to be as popular as I remember in my childhood... the
big kid models are gone, only the kiddie swings remain. Obviously,
lawyers are to blame.

Related playground question: how can a child standing in the middle of
a turntable, not touching anything else, make it rotate?

.

Relevant Pages

  • Re: Axe attack
    ... > apparently in an racist attack. ... For any "swung" weapon that has fair mass and carry through such as an axe ... swing starts or just after swing but before momentum builds. ...
    (rec.martial-arts)
  • Re: Byron Nelson and 11 victories in a row
    ... Momentum counts for something, I would think. ... the off-season while every other pro is retooling his swing and gearing up ... retooling their swings during our summer. ... I'm not arguing that one kind of streak is necessarily more impressive than ...
    (rec.sport.golf)
  • Re: Swing and momentum
    ... faster so there does his angular momentum. ... and therefore you should not expect angular momentum of the swing ... linear momentum is exchanged with the surroundings not only through ...
    (sci.physics)
  • Re: Backwards bikes
    ... Not if you ignore momentum, ... Is this momentum created from nothing, or is it pre-existing sideways ... anything else (apart from the seat of the swing). ... muscles to move his C of G sideways relative to a bicycle, ...
    (uk.rec.cycling)
  • Re: Byron Nelson and 11 victories in a row
    ... Momentum counts for something, I would think. ... the off-season while every other pro is retooling his swing and gearing up ... retooling their swings during our summer. ...
    (rec.sport.golf)