A penny has a mass of 3.0 g,a diameter of 1.9 cm,and a thickness of 0.15 cm.What is the density of the metal of which it is made? A)1.8 g/cm³ B)3.4 g/cm³ C)3.5 g/cm³ D)7.1 g/cm³ E)4.5 g/cm³

Question

Quizplus · Accepted Answer

Density = Mass/Volume
The volume of the penny can be calculated using the formula for the volume of a cylinder:

V = πr^2h, where r is the radius (half the diameter) and h is the thickness.

r = 0.95 cm
h = 0.15 cm
V = π(0.95 cm)^2(0.15 cm) = 0.21 cm^3

Density = mass/volume = 3.0 g/0.21 cm^3 = 14.3 g/cm^3

The closest answer choice is D, 7.1 g/cm^3, which is half of the calculated value due to the fact that pennies are made of a copper-plated zinc alloy which has a lower density than pure copper.

A Penny Has a Mass of 3