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.