By Dr. Leila Gonzalez
Note: This is a reprint of an article that originally appeared in the LA Times on March 11, 1999.
How do ice skaters get spinning so fast?
question submitted by Lexi Bicos, 6th Grade, Mesa View Middle
School, Huntington Beach, CA
Now that???s a perfect winter question, even here in balmy Los Angeles! It turns out that before I was a scientist, I wanted to be a dancer and took years of lessons. (But, I finally had to accept the fact that I was better at science than dance!) So, while I am now a biologist, I do know something about spinning.
If you watch figure skaters, you???ll notice that they first have to skate to build up speed (forward momentum) before they turn sharply into a spin (angular momentum). Once the spin has started, skaters often change the rate of the spin, going slower-to-faster or faster-to-slower. Now the question is, how do they do that?
What I would like you to do is to observe for yourself how skaters and dancers spin. And then, write to me about what you found out. So here are three things you can do:
|1. Watch the World Figure Skating Championship on TV (from March 21-28).|
|2. Connect to our web site and visit the Spin Lab (it's the top that is half-buried in the ground), and find the spinning figure skater whom you can make go slower or faster. There is also other information about spinning in the Spin Lab.|
|3. Try to see if you can control your own spin. Find a chair that easily spins. Make sure that it is not near any other furniture and does not easily tip over, then sit on the chair and start yourself spinning by pushing off with your feet. You should not go too fast (in other words, be careful!), but once you are spinning, lift your feet off the floor and see if there is some way you can move your arms to spin faster or slower. |
|4. Send me what you find out after you make your observations. I would be interested in knowing why you think it works! I would especially like any pictures or drawings to help me understand your ideas. Next week, a physicist will consider what you sent in, and suggest further experiments for you to do to understand angular momentum (yeah, there???s a science lesson here somewhere!).|