pressure

pressure is defined as force per unit area: p = f/a (unit: pascals (pa)). liquids and gases exert pressure due to the random motion of particles.

definition

pressure is the force acting perpendicular to a surface divided by the area over which the force acts. the same force on a smaller area creates higher pressure.

pressure and everyday examples

knife blades are sharp (small area) to create high pressure for cutting. wide shoes distribute weight over large area to reduce pressure on ground. drawing pins have small sharp points (high pressure) to penetrate surfaces. snow shoes spread weight over large area to prevent sinking.

pressure in liquids

pressure beneath a liquid surface increases with depth. deeper in the liquid, more liquid above presses down, creating greater pressure. pressure also increases with liquid density—denser liquids create higher pressure at the same depth.

pressure change with depth

∆p = ρg∆h (unit: pa), where ρ is density, g is gravitational field strength, and ∆h is change in depth. pressure increases linearly with depth in a uniform liquid.