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Re: [Phys-l] A Mechanics Question



Actually, since the roof is shingled, as usual, once the frisbee hits the roof and begins to slide upward, it hits the edge of a shingle and it flips over. Now it slides down the roof with its curved side facing downward, and its friction is quite low, and as it picks up downward speed it almost lifts off the roof and skims primarily with air friction. When it sails off the roof, Billy catches it. We are unable to answer the question of how far it landed from Billy's feet because we are not told how tall Billy is. However, if he catches it at roughly the same height as he threw it, then it is one meter from his feet.

On the other hand, if the frisbee did not flip, then it becomes stuck on the roof because the sharp edges of the bottom edge of the frisbee stick on the granules of the shingles. I know this from childhood experience, having had to get the ladder out to retrieve any frisbee that did not flip on its top when it hit the roof. I have a lot of experience climbing the ladder.


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
1 University Drive
Bluffton, OH 45817
419.358.3270
edmiston@bluffton.edu