It doesn't matter that they are different sizes or shapes. This means it is elastic. A glass is inelastic. The force the floor exerts on a dropped glass causes it to shatter. It does not return to its original shape after the force is removed so it is inelastic.
Compression strengthens an arch that supports a load.
The pieces of the arch are pushed harder against themselves by the load and this is compression. The roof is a dome which is like a 3-D arch. The load is supported by the outside walls and the roof doesn't fall because as it tries to fall it pushes against itself resulting in compression and the load being transferred to the walls. Steel wool will rust faster because it has more surface area for the oxygen to attack. No, iron is more dense than cork, but not necessarily heavier.