PHYS 1010Q Lecture Notes - Lecture 15: Vacuum Cleaner, Atmospheric Pressure, Net Force
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PHYS 1010Q Full Course Notes
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Unlike the molecules in a solid, the molecules in liquids and gasses (ie uids) can move freely from position to position by bumping into and sliding past one another. A uid, unlike a solid, will take the shape of its container. Fluids exert a pressure on the walls of a container and on other objects immersed in the. The net force is perpendicular to the surface. The weight of all the air above you exerts a force on any object immersed in that uid of air. This force per unit area of the atmosphere is called the atmospheric pressure. It is numerically equal to about 14. 7 psi or 101 kpa. The pressure decreases with increasing altitude since less air is above you. Air (unlike solids or liquids) is a compressible uid. Thus the density of air decreases as altitude increases because air expands in volume as pressure decreases.
