Experiments with magnets and conductors

Densities of materials

metal g/cm3 lb/in3 lb/ft3   lb/gal 
water 1.00  0.036  62 8.35 
aluminum 2.70 0.098 169 22.53
zinc 7.13 0.258 445 59.50
iron 7.87 0.284 491 65.68
copper 8.96 0.324 559 74.78
silver 10.49 0.379 655 87.54
lead 11.36 0.410 709 94.80
mercury 13.55 0.490 846 113.08
gold 19.32 0.698 1206 161.23

Please note that g/cm3 can also be written as gcm-3
When lb (pounds) is used in this table, this is actually pounds mass, equivalent to approximately 0.454 kg.
When a pound is used as a force (weight) in the paragraph below, it is equivalent to approximately 4.45 Newtons.
The gal (gallon) is the US gallon, not the imperial gallon.  It is equivalent to approximately 3.785 Liters.
As a volume, the US gallon is approximately equal to 3.785x10-3 m-3
For comparison, a US nickel has a mass of about 5.0g.

The lb/gal column is used for comparison to a container that would hold a gallon of milk, which weights about 8.4 lb (it's mostly water).  This is something that would be familiar to most families in the US since they would have such a container in their refrigerator at home, and they know what it feels like when they try to lift that gallon container filled with milk.

If that milk were changed to aluminum, it would weigh about 22.5 lb.  If it were changed to gold, it would weigh about 161 lb (19 gallons of water)!  Did you notice that copper is denser than iron?  A cubic foot of iron would weigh 491 lb.  A cubic foot of copper would weigh 559 lb.  Silver is even denser than copper, at 655 lb for a cubic foot.  Gold is really heavy at 1206 lb for a cubic foot.  When you see a movie of thieves carrying bars of gold, you know they are faking it!