Most of my mechanics students would get this right, because I tell them to analyze Newton's Cradle, even the ordinary one, as a succession of two-body collisions. I'll pose this on the homework next time I teach the class. Thanks! Veit On Dec 9, 2010, at 12:44 PM, Gary Antonick wrote:
Hi all,
I recently posed a simple mechanics question to a bunch of university faculty. Pretty much everyone got it wrong.
What I'm wondering is.. why? Am trying to explore this a bit. Might make an interesting story.
Here's the question. You have a Newton's Cradle. The first ball has twice the mass it normally would. You swing it so it hits the second ball. What happens? a. the last ball flies out b. the last two balls fly out c. something else
Turns out the answer is c.
No one gets this right. OK. Bill Gosper got it right. In fact, he's completely unraveling the problem. And Neil Bickford was essentially there. Maybe I should have asked more people in math-fun.
But I asked 20 university faculty (physics and engineering, mainly) and they all got it wrong. Except one guy who had to simulate it first.
What's going on?
- Gary
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