The pushing of fluid in the blood against the blood vessel wall is an example of

The answer is Hydrostatic pressure

Hydrostatic pressure is the pressure of a fluid at rest. The force of hydrostatic pressure comes from the gravity, which makes fluid with higher height will have exert higher pressure. This pressure is one of the things that limit human expedition to the deep ocean because the pressure of the water above is too high. This pressure also cause the diver to have decompression sickness.

colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.