What is the density of a roll of pennies containing 50 pennies?

Density is defined as:

Density = Mass/Volume

Now, density is an intensive property, this means that if you have 10 grams of a given material or 1000 grams of the same material, in both cases you will find the same density.

Then a roll of 50 pennies has the same density that a single penny.

The measures of a single penny are:

Mass = 2.5 g

Thickness = 1.52 mm

Radius = 9.525 mm

The coin is a cylinder, and the volume of a cylinder is:

V = pi*r^2*h

where:

pi = 3.14

r = radius = 9.525mm

h = thikness = 1.52mm

The volume is:

V = 3.14*(9.525mm)^2*1.52mm = 433.015 mm^3

The density will be:

D = 2.5g/433.015mm^3 = 0.00577 g/mm^3

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