Lecture 28: Hydrostatics - Archimedes' Principle - Fluid Dynamics - What Makes Your Boat Float? - Bernoulli's Equation

author: Walter H. G. Lewin, Center for Future Civic Media, Massachusetts Institute of Technology, MIT
recorded by: Massachusetts Institute of Technology, MIT
published: Oct. 10, 2008,   recorded: November 1999,   views: 47061
released under terms of: Creative Commons Attribution Non-Commercial Share Alike (CC-BY-NC-SA)

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1. Archimedes' Principle:

The buoyant force on an immersed body is shown to equal the weight of the displaced fluid (Archimedes' Principle). Such weight measurements can be used to determine the average density of irregular objects, and also to estimate body fat in people.

2. Floating Objects:

Most of an iceberg is submerged because its density is only a little less than the density of water. Boats float, rocks sink. Professor Lewin poses another brain teaser.

3. Stability of Floating Objects:

The center of mass of a floating object should be below the center of mass of the displaced fluid for stability; this is an important ship design concept.

4. Balloons:

The buoyant force of air on a balloon is discussed. It is demonstrated how a balloon and a pendulum behave in accelerated, closed containers.

5. Fluid Dynamics, Bernoulli's Equation:

Bernoulli's equation is presented as the conservation of energy for an incompressible fluid flow. For flow through a pipe of varying cross section, Bernoulli's equation shows that the pressure is the lowest at the smallest cross section where the velocity of the fluid is the highest. Bernoulli's equation is also applied to syphons.

6. Fluid Mechanic Magic:

Some non-intuitive demos show how ping pong balls behave in air streams.

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Reviews and comments:

Comment1 bill shaker, February 18, 2009 at 2:17 a.m.:

thank you for this very interesting piece of information i now know what archimedes priciple is

Comment2 Gus Polychronis, March 9, 2009 at 1:13 a.m.:

very good lessom
Can i ask some questions?

Comment3 grishma, December 12, 2009 at 11:18 a.m.:

Hey! Thanku very much & continue to help us.The lecture was very effective.

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