Understanding the Mass and Density of Empty Aluminum Cans

[Bcisewski]

Please correct me if wrong, but to explain why the mass of the pile is not pV = (2700 kg/m3)(1.0 m3) = 2700 kg, is because a pile of empty cans, its volume would be more of a dimension vs a weight. please explain concept if someone can. Thank you

Question: A pile of empty aluminum cans has a volume of 1.0 m3. The density of aluminum is 2700 kg/m3. Explain why the mass of the pile is not "p(alumin)*V "= (2700 kg/m3)(1.0 m3) = 2700 kg. Used from the formula p=m/V

 

[Doc Al]

The mass of some volume of stuff is $m = \rho V$, where $\rho$ is the density of whatever stuff fills the volume. Only if it were solid aluminum, would $\rho$ equal the density of aluminum. An empty can is mostly air, so the average density is much less than that of pure aluminum.

 

[Bcisewski]

Thanks for the assistance, I overlooked the cans as having space within. I guess sometime the obvious to some may be difficult to see for others.