
Possible Followups:
 How do these things compare to common items, especially to the densest things you can think of?
 What about the density of a neutron star (1.5x10^{15} g/cm^{3})?
Extension:
For those classes with graphing calculators, this lab is easily extended. Enter the radius values as L1 and the density values as L2. Perform a Power Regression to find a fit to the data. What sort of relationship do you find? Trace the values of X back to the point that it equals the radius you must achieve to have your aluminum foil star become a black hole. What is the Y value at that point? Alternatively, have them enter the required X value into the fit equation and calculate the Y value that corresponds to it  in other words, at the radius required to make our foil star a black hole, what is the density?
Based on an idea from Jeffrey F. Lockwood, Sahuaro High School, Tucson, AZ.
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