Jayjay

In another thread at Evolution/Creation forum, someone quoted Hovind's claim that when you spin a merry-go-round with kids in it, and a kid is hurled off, he or she would be spinning in the same direction as the merry-go-round. Now, I do realize that the kid's trajectory is a straight line, but what my feeble mind doesn't quite grok is the spinning... would angular momentum (is that what it's called?) be preserved, so that the unlucky child would indeed be rotating while flying away from the merry-go-round, or is there some reason why he or she wouldn't?

simian

I don't know the answer to what you are asking directly. Angular momentum is obviously conserved, but does that mean that every particle flying off has the same angular velocity? What I do know is that once the kid flys off the merry-go-round they can hit other objects which can change the kid's angular momentum. For example, if the kid's head hits a tree (or the feet of another kid), the angular speed can be increased or decreased.

Simian

Abacus

They would not have to be spinning. Hovind has a very flimsy grasp on physics.

fando

Never mind, i'm not thinking straight.

[ December 03, 2002: Message edited by: fando ]</p>

NialScorva

Well, the parts of your body further away from the center of rotation would have a higher velocity than those on the inside, so there would be some torque. In a fluid, it gets a fair bit more sketchy that I'm willing to deal with.

Mr. Sammi

NialScorva, is that not higher angular velocity further away from the center of rotation?

What the point here is, is the translation of angular momentum to linear momentum AND what constrains angular velocity from retaining its pitch. This has to do with the rigidity of the body in question.

Sammi Na Boodie ()

**makTHRAX**

They would fly off at in a direction tangent to the point of the circle (the merry-go-round in this instance). They would also fly off at a speed equal to the merry-go-round (or the kid on the merry go round)'s angular velocity multiplied by the radius of the marry go round. Moreover, the kid jumping off the merry-go-round would cause the merry-go-round to increase in angular velocity, possibly hurling the other kids off and triggering massive litigation against the owners of the playground.
(i just finished a merry-go-round problem for physics...it's kinda scary how this thread exists at this point in time)
thx,
makTHRAX

beausoleil

A child is not a point mass.

Suppose the kid holds his arms outstretched as he's on the merry-go-round, left towards the centre, right away. If you think about his arms, each time he goes round the merry go round, you'll see that he spins on his own axis once.

It's a bit like our Moon. The Moon spins on its axis once per orbit so it keeps the same face towards the Earth. If the Earth was magicked away, would the moon stop spinning?

Nice to see a fellow Knoxvillian (I live there sometimes)

[ December 03, 2002: Message edited by: beausoleil ]</p>

Abacus

What if the merry-go-round were magicked away? Would the children be left spinning?

fando

The Moon would follow the tanget of its orbit the instant the Earth disappeared. Recall that the velocity vector of an object in a circular path is tanget to the circle.