A beaker. Simply fill the beaker with a known quantity of liquid. Drop the object into the beaker, and measure the difference in the fluid levels.
the water displacement method
It depends on what the second method is!
equal the density of any other piece, assuming that the original cube was made of the same uniform substance.
uh, a pyramid.
scaphoid
Google "Archimedes' Principle" and see if that gives you a clue...
You can push it under water / under the liquid's surface, and measure the displacement of liquid.
Finding the center of gravity of an irregularly shaped object can be done using the plumb line method.
the water displacement method
Mass divided by Volume = Density. Or use the displacement method for an irregularly shaped object.
Asteroid
you would use the water displacement theory
If the object in question is water proof, and small enough. You can measure the amount of displaced water when it is placed in a tank full of water, this may not work for a lot of things but it can help when attempting to measure some objects.
Tight
Use volume displacement method.
Yes. It doesnt have to be a irregular even though sometimes it is easier just to do the math... for a rectangular object. l x w x h= volume
Take an amount of water of which you know the volume. Drop the object in the water. Find the difference