Magnus Effect
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Magnus Effect
Jonathan Sanderson
Download film (right-click)Adult , Demonstration , Explanation , Physics
A simple and neat explanation of the physics behind footballs curving gracefully through the air.
Director's Notes:
We’ve all seen footballs kicked so they fly in a graceful curve (usually, in our case, away from the goal rather than heroically into the top corner). How does that work? Wendy Sadler explains, and shows you with a neat do-it-yourself-it’s-easy demonstration.
Really, do. Grab a couple of plastic cups, some tape, and some elastic bands. Fun!
You can find out more about Wendy and her company Science Made Simple at their website.
SciCast Notes:
Wendy’s a professional, and it shows. We shot this film in about 20 minutes, after a training day with her science communication company. Rattling out a clear and concise explanation can be a real challenge, but here Wendy makes it look easy.
I didn’t quite know what I was going to shoot when we started, so for once I broke my own rules and held the camera by hand. However, I slapped a big wide-angle adaptor on the front, which gives the wonderful exaggerated perspectives you see, and things like ducking low to see the underside of the cups just made sense as we went along.
The other ‘rule’ I broke is that I relied on the camera’s built-in microphone. The room was quiet, and I was standing within a metre or so of Wendy, so the result is fine. A ‘proper’ microphone would have been a bit less sharp, but when there’s limited fiddling time, work with whatever you have!
— Jonathan
excellent idea, and a marvelous demonstration, most charmingly presented! HOWEVER... Suppose the two cups were back-spinning as they leave the elastic band at such a rate as would correspond to them rolling, without slipping, on the roof: wouldn't this mean the speed of the upper surface of the cups relative to the air(which is equivalent to imaginary roof) is ZERO ? ? ? How can the relative speed (cup/air) on top be faster than underneath?
My best wishes and thank you!!!
Ronald