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Re: [Phys-l] [ap-physics] The Swinging Bucket Problem






The string is not touching the water. Hence the string is exerting no
force on the water.
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I'm not sure how that answers the question of "how fast do you spin the
bucket". There really is no minimum speed per se. The bucket always
falls with the water and nothing spills until it hits the floor. You can
always hold a bucket in your hand and simultaneously tip it over and
release it - no spill as it falls.

What you are really calculating is the speed that the string goes slack.
The problem has nothing to do with spilling because the water can't
spill! Therefore there is no point in calculating the force of the
bucket on the water - bogus problem!

This is very similar to our recent discussion of the barometer question.
If you have a question in mind that you wish to ask the students - make
sure that's what you actually ask them. The question "how slowly can I
swing the bucket so that the water will not fall out" is a meaningless
question since the water can't fall out no matter what you do.

Bob at PC