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What's Your Angular Momentum When You Spin On an Office Chair?

I've worked out mine because I'm applying to Uni, and I've shoved it into my personal statement. I want to make sure I have a reasonable (approximate) answer, so if you fancy working out an approximation of your angular momentum, it would be really useful. 

It's also quite a fun experiment. Don't get too dizzy. 
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  • Asked by LaexD
  • on 2010-10-01 17:24:11
  • Member status
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Categories: Domestic Science.

Tags: physics, mechanics, Momentum, angularmomentum, experiment, officechair.

 

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 antoniolifer says:

Exactly the same as you had before spining! Isn't that what the conservation of angular momentum says? Shouldn't you be doing your homework by yourself?

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Tags: physics, mechanics, Momentum, angularmomentum, experiment, officechair.

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posted on 2010-10-04 20:39:46 | Report abuse

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 shornoff says:

Angular momentum, like linear momentum is only conserved in a closed system. If you put energy into the system by spushing on the floor to spin the chair then angular momentum is not conserved!

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Tags: physics, mechanics, Momentum, angularmomentum, experiment, officechair.

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posted on 2010-10-04 21:00:42 | Report abuse

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 shornoff says:

Assuming I'm an 80 kg cylinder of radius 0.25 m I have a moment of inertia of 0.5 X 80 X 0.25 squared.

I rotate at about π radians per second

So L approximates to 7.5 Js How does compare with your guesstimate?

If I extend my arms whilst rotating my radius increases enormously so L much bigger.

sssss
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Tags: physics, mechanics, Momentum, angularmomentum, experiment, officechair.

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posted on 2010-10-04 20:56:43 | Report abuse

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 LaexD says:

My original answer was 6.97 Js, but I modelled myself as a point mass when I did it. If, however, I change my calculation so that I model myself as a cylinder (which is much more accurate than being a point mass), I get 3.49 Js. Seeing as I have a mass of 45kg, and measured my chair/approx. radius to 0.22m, this seems about right :). 

Thanks so much for your help, it's been really useful! I can finish my personal statement much more peacefully now. 

sssss
 (1 vote) average rating:5

Tags: physics, mechanics, Momentum, angularmomentum, experiment, officechair.

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posted on 2010-10-05 20:01:22 | Report abuse

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