Ch 13 - Static Fluids

Pressure

fluid exits perpendicular to the surface → pressure must be perpendicular

• constant collisions w/ walls of container & objects

• need a F to change the direction of atoms’ molecules

Pascal’s Principle

inc in P of static, enclosed fluid at 1 place in the fluid = uniform inc in P t/o fluid

• P of fluid in closed container has to be the same everywhere

Glaucoma

P incs in the front of the eye

• transmitted everywhere

• affects vision → changes shape of eyeball

• damages BVs, optic nerve, retina

• more F on everything

Pascal’s Principle: Application

exert F on 1 piston to move other → P will always be the same

• change the size of the piston = get a diff F from the P

• larger area = exert larger force

• P₁= P₂ → F₁/A₁ = F₂/A₂

Depth & Pressure

P incs w/ depth

• gauge pressure → the pressure relative to atmospheric pressure, which increases with depth due to the weight of the fluid above

• absolute pressure → the total pressure exerted on an object, including atmospheric pressure, and increases with depth in a fluid.

Would the pressure on your ears be greater when swimming 3m deep in the middle of a swimming pool or the Atlantic ocean?

greater in the Atlantic

• more dense fluid, water above is heavier

Barometers

used to measure pressure

• long closed tube filled w/ mercury * inverted into a dish of mercury (dense liquid)

• P_atm = p_Hggh

• 1 atm = 760 mmHg

Open Tube Manometer

1 end open to atm, other end connected to P, fillled w/ mercurg

• P_B= P_atm + p_Hggh

• P_B = P_A = P

• P = P_atm + p_Hggh