Subject:
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RE: VERY [OT] Feathers 'n Lead...
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Mon, 12 Jul 1999 15:49:33 GMT
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Viewed:
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1640 times
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> > > I remember seeing some footage of a feather and a hammer? being
> > > dropped by an astronaut on the moon's surface. They both hit the ground at
> > > the same time, which proves to mee that even a single feather is as heavy
> > > as a hammer, so I could assume that a HUGE 25 lb bag of feathers weighs even
> > > MORE than a bag of lead.
> >
> > the dropping of the objects on the moon was to prove that when 2 objects are
> > dropped from the same height in an environment with little or no friction
> > they will hit the ground at the same time. both bags weigh the same, one is
> > more bulky and due to size will have a greater inertia because of the energy
> > needed to move it, both will require the same ammount of work.
>
> I think the original poster was putting his tongue firmly in cheek there.
> BTW, the dropping of objects would be a second experimental proof that gravity
> affects all objects equally regardless of weight. Best test being in a vacuum
> where you could drop two wildly different objects with no air friction
> component.
Sorry for the extra quoting here, but the thread was a bit old...and just for
everyone's info, both bags have the SAME mass, so they have the same first
moment of inertia....I think. The shape of the object generally affects the
SECOND momemnt of inertia when we ask it to spin...
Dennis, you are right - my tongue WAS firmly in cheek. There is a demo at our
Science Centre in Toronto with a coin and a feather dropping in a vacuum, and they
actually hit the ground at the same time. I think the original version of the
experiment was performed at the Tower of Pisa, which had a neat cantelievered
structure (tongue in cheek) from which it was easy to drop two objects of
different weights that were negligibly affected by air resistance. They hit
the ground at the same time too!
There's a really wierd demo too. They have a hoop of iron, and a disk of wood
that have the same diameter and the same weight. Roll them down identically
inclined ramps and which one accelerates faster????
The solid wooden disk. Its second moment of inertia is less than the iron hoop,
and so will accelerate faster down the ramp.
That's it for now....
Cheers,
Ralph Hempel - P.Eng
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Message is in Reply To:
 | | Re: VERY [OT] Feathers 'n Lead...
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| (...) I think the original poster was putting his tongue firmly in cheek there. BTW, the dropping of objects would be a second experimental proof that gravity affects all objects equally regardless of weight. Best test being in a vacuum where you (...) (25 years ago, 12-Jul-99, to lugnet.robotics.rcx)
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