Difference between revisions of "Measuring hard things with easy experiments"

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(Measuring the speed of light using chocolate chips and a microwave oven)
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http://superpositioned.com/articles/2006/03/09/measure-the-speed-of-light-with-chips
 
http://superpositioned.com/articles/2006/03/09/measure-the-speed-of-light-with-chips
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== Calculating PI with a box of toothpicks ==
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Take a box of N toothpicks - each of length L.  Find a floor with parallel lines on it - a tiled floor or one made of planks will do.  (If you use tiles you need to pick one set of parallel lines to use. eg pick just the 'north-south' lines between them and ignore the east-west lines.)  The distance between the parallel lines is D - and D must be bigger than L.
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Now - dump out all of the toothpicks onto the floor from a good height so they land pretty much at random.  Now, count the number of toothpicks that cross one of the lines on the floor...call that number 'C'.
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OK - so all you need to do is to calculate:
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  PI = 2 x L x N / ( D x C )
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...tadaaaa!  Of course you need to drop an awful lot of toothpicks to get a precise answer...especially if the distance between the lines on your floor is much bigger than the length of the toothpicks.

Revision as of 15:37, 6 May 2009

Here are some links to experiments that allow you to measure impossibly-difficult-sounding things using everyday objects:

Measuring the thickness of a human hair using a laserpointer and a tape measure.

http://www.fysikbasen.dk/English.php?page=Vis&id=87

Measuring the speed of light using chocolate chips and a microwave oven

http://superpositioned.com/articles/2006/03/09/measure-the-speed-of-light-with-chips

Calculating PI with a box of toothpicks

Take a box of N toothpicks - each of length L. Find a floor with parallel lines on it - a tiled floor or one made of planks will do. (If you use tiles you need to pick one set of parallel lines to use. eg pick just the 'north-south' lines between them and ignore the east-west lines.) The distance between the parallel lines is D - and D must be bigger than L.

Now - dump out all of the toothpicks onto the floor from a good height so they land pretty much at random. Now, count the number of toothpicks that cross one of the lines on the floor...call that number 'C'.

OK - so all you need to do is to calculate:

  PI = 2 x L x N / ( D x C )

...tadaaaa! Of course you need to drop an awful lot of toothpicks to get a precise answer...especially if the distance between the lines on your floor is much bigger than the length of the toothpicks.