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Here it is:<br />

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Use the fact that a typical proton is spherical and has a diameter of 1 x 10^-13 cm and a mass of 1.67 x 10^-24 grams, compute the density of a proton. A common material such as water has a density of 1 grams per cubic centimeter. Density is the mass per volume.<br />

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Here are the possibles answers (multiple choice)<br />

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A. 3 x 10^15 grams/cm^3 <br />

B. 2 x 10^40 grams/cm^3 <br />

C. 3 x 10^-16 grams/cm^3 <br />

D. 45 x 10^18 grams/cm^3 <br />

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I know that I need to use the formula for finding the volume of a sphere "4/3 Pi r^3" but after that I am lost.<br />

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Please help and thanks in advance!!<img src="/images/smilies/smile.gif" border="0" alt="" title="Smile" class="inlineimg" />