Three flakes of lead

Factual Questions
1

Forensic pathology question:

Three flakes of lead:

  1. 0.5 mm in diameter,
  2. 1.0 mm in diameter,
  3. 2.0 mm in diameter,

each 0.5 mm thick.

How much do they weigh total, in grains?

2

0.36

3

Assume they’re roughly cylindrical.

Volume of a cylinder is pi*r[sup]2[/sup]*height

The radii are .025 cm, .05 cm, and .1 cm.

pi0.000625.05 = .000098 cm[sup]3[/sup]
pi0.0025.05 = 0.00039 cm[sup]3[/sup]
pi0.01.05 = 0.00157 cm[sup]3[/sup]

density of elemental lead is 11.34 gram/cubic centimeter

=0.00111 g or 1.11 mg
=0.00442 g or 4.42 mg
=0.0178 g or 17.8 mg

Total 23.3 mg

a grain is 64.80 mg

=0.36 grains
ON PREVIEW - That’s pretty amazing we came to the same answer, yoyodyne!

4

How many answers are there?

5

Well, there’s the one where I move the decimal the wrong number of places, but I didn’t give that one. (I don’t think…)

Or there’s the one where one doesn’t assume the flakes are cylindrical. But I didn’t give that one.

Then there’s another where one makes a rounding or significant figures error. Actually, it’s possible we both gave that one…

6

Thank you, yoyodyne and Randy, for those quick and matching answers.