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Science Idle

The Physics of Jump Rope 29

Posted by samzenpus
from the because-he-can dept.
sciencehabit writes "Last year, Jeffrey Aristoff and Howard Stone, mechanical engineers at Princeton University, were at the gym waiting for a pickup game of basketball. To warm up, Stone started jumping rope. As the rope whizzed over the head of his colleague, Aristoff wondered, 'Is it known how jump ropes bend in the wind?' A few literature searches later, he concluded that the answer was, 'not really.' Now, the two have solved the problem themselves."
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The Physics of Jump Rope

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  • by Anonymous Coward on Wednesday November 02, 2011 @06:28PM (#37927598)

    Reminds me of a guy named Richard Feynman who did some "meaningless" but fun physics research:

    Within a week I was in the cafeteria and some guy, fooling around, throws a plate in the air. As the plate went up in the air I saw it wobble, and I noticed the red medallion of Cornell on the plate going around. It was pretty obvious to me that the medallion went around faster than the wobbling.
              I had nothing to do, so I start to figure out the motion of the rotating plate. I discover that when the angle is very slight, the medallion rotates twice as fast as the wobble rate -- two to one. It came out of a complicated equation! Then I thought, "Is there some way I can see in a more fundamental way, by looking at the forces or the dynamics, why it's two to one?"
              I don't remember how I did it, but I ultimately worked out what the motion of the mass particles is, and how all the accelerations balance to make it come out two to one.
              I still remember going to Hans Bethe and saying, "Hey, Hans! I noticed something interesting. Here the plate goes around so, and the reason it's two to one is..." and I showed him the accelerations.
              He says, "Feynman, that's pretty interesting, but what's the importance of it? Why are you doing it?"
              "Hah!" I say. "There's no importance whatsoever. I'm just doing it for the fun of it." His reaction didn't discourage me; I had made up my mind I was going to enjoy physics and do whatever I liked.
              I went on to work out equations of wobbles. Then I thought about how electron orbits start to move in relativity. Then there's the Dirac Equation in electrodynamics. And then quantum electrodynamics. And before I knew it (it was a very short time) I was "playing" -- working, really -- with the same old problem that I loved so much, that I had stopped working on when I went to Los Alamos: my thesis-type problems; all those old-fashioned, wonderful things.
              It was effortless. It was easy to play with these things. It was like uncorking a bottle: Everything flowed out effortlessly. I almost tried to resist it! There was no importance to what I was doing, but ultimately there was. The diagrams and the whole business that I got the Nobel Prize for came from that piddling around with the wobbling plate.

    - Richard Feynman, Surely You're Joking, Mr. Feynman

"There is nothing new under the sun, but there are lots of old things we don't know yet." -Ambrose Bierce

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