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



This has been one of my favorite 'discussion topics' when on field trips with our HS students (who are preselected for Science & math interest).

For state fair trips I can make sure that someone will bring back a suitable balloon.
For other trips (camping, robotics etc.) it may take a while for us to gather the necessary equipment.

The MOST important thing is to have a rousing discussion of what will happen and WHY.

I remember one particular student who was bound for MIT and had had ALL the 'advanced' physics and math courses.
He could argue convincingly for EITHER result and was really quite unable to come up with the 'basic' force diagram that would convince the other (less advanced) students.

He's done well at MIT but STILL may not be able convince anyone of the right answer.


On Apr 22, 2009, at Apr 22(Wed) 1:33 , Bill Nettles wrote:

Experience (repeatably) tells me it moves forward relative to its original position in the car.

Bill Nettles

"Richard A. Lindgren" <ral5q@virginia.edu> 4/21/2009 10:42 am >>>
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