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Hi PhysListers,
I was explaining away the the easy rolling
of the boiled egg (as compared to raw egg)
as due to the reduced moment of inertia of
the boiled egg. But there was another opinion as in the mail below.
I would like to hear your thoughts
Jaya
----- Begin Included Message -----
From J.Jayasanker@infineon.com Mon Oct 2 09:21 SGT 2000
From: J.Jayasanker@infineon.com
To: jjaya@ezmsgp.hl.siemens.de
Subject: FW: gamesman problems - mechanics type !!
Date: Mon, 2 Oct 2000 09:20:55 +0800
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-----Original Message-----
From: Don Mack [mailto:d.mack@ieee.org]
Sent: Saturday, September 30, 2000 1:01 AM
To: J.Jayasanker@infineon.com
Subject: Re: gamesman problems - mechanics type !!
Mr. Jayasanker:
I don't think that boiling an egg changes its moment of inertia
significantly. It still has a yoke and egg white. Some of the potential
energy of a raw egg is used by the internal friction required to get the
contents up to the speed of the shell. This friction energy reduces the
egg's kinetic energy, making it roll slower that the boiled egg.
Here is a second opinion by one of my colleagues:
I don't believe for a minute that the moment of inertia changes when
an egg is boiled. Certainly the mass doesn't change and I can't
believe the distribution of mass within the shell changes, either.
The difference, I'm pretty sure, is in the viscosity. Have you ever
compared spinning first a hard boiled egg, then a raw egg on a
counter top? It's obvious which is which, the hard egg spinning much
longer than the raw. The fluidity of the raw egg means it is lossy
and absorbs the kinetic energy as the egg undergoes acceleration,
either positive or negative. The hard egg, being solid, has minimal
loss. I feel pretty sure that your student's experience with a
rolling egg can be explained that way. Make sense?
----- End Included Message -----