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Old Nov 14th 2017, 05:08 AM   #1
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Join Date: Nov 2017
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Please help! How big does the semi circle need to be?

Hello there,

The problem that one of my students came to me with is:

I want to fit 240 grams of chocolate into a semi circle, so could you tell me the diameter I need to make the semi circle in mm?

I have worked out that the volume of a 100mm diameter semi circle is 5235 cubic mm, but then how do I apply that?

Please help! Many thanks!

Last edited by JJLondon; Nov 14th 2017 at 05:35 AM.
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Old Nov 18th 2017, 06:18 AM   #2
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Join Date: Aug 2010
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A "circle" or "semi-circle" doesn't have any volume at all! Do you mean "hemi-sphere" or perhaps a semi-circle with a given height (a cylinder)? I have no idea how you got 5283 cubic mm. A hemisphere with radius 100 mm has volume 2094395 cubic mm. A semi-circle with radius 100 mm has area 15708 square mm. The volume depends upon the height. In order to have a volume of 5235 cubic mm, height would have to be 3 mm. Are you assuming that?

In any case you would need to have a certain volume of chocolate, in cubic mm, not mass in grams. To determine that you need to divide the given "240 grams" by the density of the chocolate- and that varies with the type of chocolate though it averages around 1325 kilograms per cubic meter= 0.001325 grams per cubic mm.
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