Re: [Phys-l] balloon floating in air in car

["LaMontagne, Bob" <RLAMONT@providence.edu>]

Density is not really a player here. A car filled with water would give the same effect - but the density of water is essentially independent of depth over these distances.

Bob at PC

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of David Willey
Sent: Tuesday, April 21, 2009 11:50 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] balloon floating in air in car

The balloon moves forward as the denser air moves to the back of the 
vehicle,
cheers,
David

Richard A. Lindgren wrote:
> Hello,
> Another variation. How about a helium filled balloon floating  gently up 
> against the roof in the back seat of your car. What happens when the car 
> accelerates forward?
> Richard at UVa
>
> On Tue, 21 Apr 2009 11:25:39 -0400
>   "LaMontagne, Bob" <RLAMONT@providence.edu> wrote:
>   
> > Obviously the ball goes up with the elevator.
> >
> > Bob at PC
> > ( mg = rho g V,  g increases on both sides of the equation, so V doesn't 
> > change?)
> >
> > -----Original Message-----
> > From: phys-l-bounces@carnot.physics.buffalo.edu 
> > [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Anthony 
> > Lapinski
> > Sent: Tuesday, April 21, 2009 8:38 AM
> > To: phys-l@carnot.physics.buffalo.edu; tap-l@lists.ncsu.edu
> > Subject: [Phys-l] ball floating in elevator
> >
> > A ball is floating in a beaker of water in an elevator. What happens to
> > the ball when the elevator accelerates upward? Good question for your
> > "bright" students!
> >
> > Think about this before checking out the video below.
> >
> > http://www.youtube.com/watch?v=OXuYWCWIaJI
> >
> > I guess you could demonstrate an elevator accelerating downward -- free
> > fall -- by dropping a (plastic) beaker above a garbage pail to see what
> > the ball does while falling. Might be hard to observe this fast motion, so
> > a video camera would be useful.
> >
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> >     
>
> Dr. Richard A. Lindgren
> Research Professor of Physics and
> Director of Masters of Arts in Physics Education Program
> Institute of Nuclear and Particle Physics
> Department of Physics
> University of Virginia
> P.O. Box 400714
> Charlottesville, VA 22904-4714
> UVa Office 434-982-2691
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>   


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