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Bernoulli’s, Pascal’s, & Archimedes’ Principles. Principles of Lift, Buoyancy, and Pressure. A. Bernoulli’s Principle. As the Velocity (speed) of a fluid increases , the Pressure exerted by the fluid decreases Why?. Curve Ball. A. Bernoulli’s Principle. Airplane lift.
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Bernoulli’s, Pascal’s, & Archimedes’ Principles Principles of Lift, Buoyancy, and Pressure
A. Bernoulli’s Principle • As the Velocity (speed) of a fluid increases, the Pressure exerted by the fluid decreases • Why?
Curve Ball A. Bernoulli’s Principle Airplane lift View airplane wings explanation.
B. Archimedes’ Principle • The buoyant force on an object in a fluid is equal to the weightof the fluid displaced by the object
B. Archimedes’ Principle • The upward force of a Fluid exerted on an object. • What is the downward Force exerted on an object? Gravity
B. Archimedes’ Principle From Archimedes’s Principle : Buoyant Force = Weight of fluid displaced = mg (note : F = ma) = Vg (note : = m ) V Thus FB = V g FB = Buoyant Force or Upward thrust = Density of fluid V = Volume of fluid displaced or the volume of the object that immersed in the fluid. g = force of gravity
Mass = 20g B. Archimedes’ Principle Volume = 20ml Mass of Fluid= 20g
Gravity = 20 Buoyant Force = 20 B. Archimedes’ Principle Object is in Liquid
Mass = 50g B. Archimedes’ Principle Volume = 20ml Mass of Fluid= 20g
Gravity = 50 Buoyant Force = 20 B. Archimedes’ Principle Object SINKS
Mass = 30g B. Archimedes’ Principle Volume = 60ml Mass of Fluid= 60g
Gravity = 30 Buoyant Force = 60 B. Archimedes’ Principle Object Floats
B. Archimedes’ Principle • Recall Fg= mg and Fb= V g • If the buoyant force is less than the force of gravity (Fb<Fg) the object will sink • If the buoyant force is greater than the force of gravity (Fb>Fg) the object will float • If the buoyant force is equal to the force of gravity (Fb=Fg) the object will maintain the same depth
B. Pascal’s Principle • pressure applied to a fluid is transmitted unchanged throughout the fluid View hydraulics explanation.
WORK: 1000 N = F2 250 m2 10 m2 B. 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 N A = 250 m2 Plunger: F = ? A = 10 m2 (1000N)(10m2)=(250m2)F2 F2= 40 N
Force ? Force = 15,000 N A B B. Pascal’s Principle Area of A = 8 cm2 Area of B = 50 cm2 How much force must you apply on A to lift the object on B?
A B B. Pascal’s Principle FA= 15,000N 8 cm2 50cm2 FA =(8 cm2)(15,000 N) 50cm2 FA = 2,400 N