Fluids (part 5)
Introduction to Archimedes' principle and buoyant force.
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Khan Academy
------------
Title: Fluids (part 5)
Description: Introduction to Archimedes' principle and buoyant force.
Url: http://www.khanacademy.org/video/fluids--part-5?playlist=Physics
InternalName: fluids--part-5
YoutubeId: vzID7ds600c
Keywords: Archimedes, principle, buoyant, force, physics, pressure
My Notes
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A cup of liquid such as water
the pressure at any point is acting equally in all directions
the water is stationary
Archimedes Principle
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a cube in the water
What is the net force acting on the cube?
A point pT on top of the box will have a lower pressure than a point pB on the bottom of the box.
net force Fn = pB * d^2 - pT * d^2
where d^2 is the surface area of a side
Fn = (pB - pT) * d^2
the cube is submerged an amount h
the distance between the top of the cube and the surface of the water
pT = density of liquid * h * g
pB = density of liquid * (h + d) * g
Fn = (phg + dpg - phg) * d^2
where p = rho = density
Fn = (dpg) * d^2 = d^3 * p * g
where d^3 = the volume of the cube
= the volume of the water displaced by the cube
Fn = mass * g
= weight of the liquid displaced
Archimedes Principle
the net force acting upwards = the weight of the liquid being displaced
Buoyant Force
net upward force because there's more pressure on the bottom than on the top
this makes things float
there are no specific problems presented in this video
</Notes>
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