Re: [asa] Physics poser

From: Don Nield <d.nield@auckland.ac.nz>
Date: Wed Sep 17 2008 - 23:22:54 EDT

Jim's question is new to me. After a few minutes thought I am predicting
that the balloon will move forward in the car, for the same reason that
it rises in a stationary car -- a buoyancy (Archimedes principle)
effect, when, relative to the car, the balloon is subject to a negative
horizontal acceleration.
Don

Jim Armstrong wrote:
> Well, here's my favorite physics question:
>
> Imagine your car at rest at a stop light. A helium filled balloon
> lolls freely at rest at the center of the car's ceiling.
> Now imagine that the light turns green and you accelerate through the
> intersection.
> You notice that the balloon moves quite purposefully as you accelerate.
> Question: which direction did the balloon move, and why?
> Followup: set the experiment up for real and see what happens. Any
> surprises? Any explanation "adjustments" required?
>
> If you get it right, you'll have to settle for the satisfaction, I'm
> afraid!
>
> JimA [Friend of ASA]
>
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Received on Wed Sep 17 23:23:49 2008

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