Embed Size (px)
Citation preview
Ch. 3 & 4Ch. 3 & 4Motion & ForcesMotion & Forces
VII. Forces in Fluids (Ch. 8.5) Archimedes’ Principle Pascal’s Principle Bernoulli’s Principle
A. Archimedes’ PrincipleA. 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’ PrincipleA. Archimedes’ Principle
Bouyant Force upward force exerted by a fluid on an
immersed object bouyant force > weight
bouyant force = weight
bouyant force < weight
balloon rises
balloon sinks
balloon floats
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.
A. Archimedes’ PrincipleA. Archimedes’ Principle
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.
View animations produced by students at Poly Prep Country Day School in Brooklyn, New York.
View Buoyancy JAVA Applet.
B. Pascal’s PrincipleB. Pascal’s Principle
Pascal’s Principle pressure applied to a fluid is
transmitted unchanged throughout the fluid
A
FP
View hydraulics explanation.
2
2
1
1
A
F
A
F
B. Pascal’s PrincipleB. Pascal’s Principle 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 NA = 250 m2
Plunger:F = ?A = 10 m2
(1000 N)(10 m2)=(250 m2)F2
F2 = 40 N
2
2
1
1
A
F
A
FWORK:
1000 N = F2
250 m2 10 m2
C. Bernoulli’s PrincipleC. Bernoulli’s Principle
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 PrincipleC. Bernoulli’s Principle
Airplane lift Curve Ball
View airplane wings explanation.
C. Bernoulli’s PrincipleC. Bernoulli’s Principle
Funnel Demos
View funnel explanation. View inverted funnel explanation.
C. Bernoulli’s PrincipleC. Bernoulli’s Principle
Venturi Effect
fluids flow faster through narrow spaces causing reduced pressure
EX: garden sprayer, atomizer, carburetor
C. Bernoulli’s PrincipleC. Bernoulli’s Principle
View atomizer explanation.
Venturi Effect - Atomizers
