1. Notice that a silo has bands around it to give it strength. Notice also that these bands are closer together near ground level and are spaced farther apart near the top of the silo. Why is this so?2. The density of a rock doesn't change when it is submerged in water, but YOUR density does change when you are submerged. Why?
Grain in a silo behaves as a semi-fluid, since the grains are somewhat mobile. In a water tank, you experience increasing pressure with depth due to the mass of water above. A person's density in water may change a little if they hold their breath and dive down in the deep end of a pool. The increasing pressure will compress the air stored in the lungs, so the overall volume of the body diminishes slightly while the mass remains constant.
Neither rock's nor ours density changes. It is relative density which matters. Relative to the water.
