Day 62, Tuesday, 1 December, 2015 Fluid Mechanics Fluids Pressure Pascal’s Principle Archimedes's Principle Pressure at depth

Fluids

No shape of their own Pressure Pascal's Principle Archimedes's principle Pressure at depth

Fluids Fluids have no shape of their own Liquids have no shape but definite volume Gases have no shape and variable volume

Density D = M/V ρ = m/vρ (rho) ≡ density

Pressure P = F/A Perpendicular to surface

Pascal's Principle Blaise Pascal 1623 – 1662, French physician Pressure is transmitted undiminished through a fluid. Shape has no effect. Pressure is transmitted equally to every point in the fluid and to the walls of the container.

Pressure depends on the depth, not on the shape

Hydraulic Press

Archimede's principle Archimedes – Greek scientist 212 B.C. F b = ρVg Density of a fluid is rho or ρ The magnitude of the buoyant force is equal to the weight of the displaced fluid

Pressure at depth P = F/A = mg/A d =m/v => m = dv P = dvg/A v =Ah P = dAhg/A P = dhg d = ρ P = ρgh

Summary P = F/A Pascal’s principle: Pressure is transmitted undiminished through a fluid. (shape has no effect) Archimedes's principle: Buoyant force = weight of displaced fluid Pressure at depth: P = ρgh

Credits Fluid graphic net.com/force/sf000.htm net.com/force/sf000.htm Pressure cartoon cs_Cartoons.html cs_Cartoons.html

More Credits Pressure at depth, Pascal’s vases Physics/Physica105/Phy105- lessons/lesson7-105.htm Hydraulic Press picture hyperphysics.phy- astr.gsu.edu/.../hpress.gif