# VII. Forces in Fluids (Ch. 8.5)

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VII. Forces in Fluids (Ch. 8.5)
Ch. 3 & 4 Motion & Forces VII. Forces in Fluids (Ch. 8.5) Archimedes’ Principle Pascal’s Principle Bernoulli’s Principle

A. Archimedes’ Principle
Fluid matter that flows liquids and gases Buoyancy the ability of a fluid to exert an upward force on an object immersed in it

A. Archimedes’ Principle
Bouyant Force upward force exerted by a fluid on an immersed object bouyant force > weight balloon rises bouyant force < weight balloon sinks bouyant force = weight balloon floats

A. Archimedes’ Principle
the bouyant force on an object in a fluid is equal to the weight of fluid displaced by the object Very little water needs to be displaced in order to cancel weight  ball floats on surface. More water needs to be displaced in order to cancel weight  ball floats lower in the water. Not enough water is displaced in order to cancel weight  ball sinks. View Buoyancy JAVA Applet. View animations produced by students at Poly Prep Country Day School in Brooklyn, New York.

View hydraulics explanation.
B. Pascal’s Principle Pascal’s Principle pressure applied to a fluid is transmitted unchanged throughout the fluid View hydraulics explanation.

B. Pascal’s Principle Platform: 1000 N = F2 F = 1000 N 250 m2 10 m2
A car weighing 1000 N sits on a 250 m2 platform. What force is needed on the 10 m2 plunger to keep the car from sinking? GIVEN: Platform: F = 1000 N A = 250 m2 Plunger: F = ? A = 10 m2 WORK: 1000 N = F2 250 m m2 (1000 N)(10 m2)=(250 m2)F2 F2 = 40 N

C. Bernoulli’s Principle
as the velocity of a fluid increases, the pressure exerted by the fluid decreases EX:airplane lift, curve balls

C. Bernoulli’s Principle
Airplane lift Curve Ball View airplane wings explanation.

C. Bernoulli’s Principle
Funnel Demos View funnel explanation. View inverted funnel explanation.

C. Bernoulli’s Principle
Venturi Effect fluids flow faster through narrow spaces causing reduced pressure EX: garden sprayer, atomizer, carburetor

C. Bernoulli’s Principle
Venturi Effect - Atomizers View atomizer explanation.