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The fundamental aspects of these Lecture Slides are : Mass Density, Continuous Piece, Liquid, Solid, Occupies, Dimensionless Measure, Specific Gravity, Ratio, Substance, Pressure
Typology: Slides
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A small, continuous piece of a substance (solid, liquid or gas) of mass Δ M occupies a volume Δ V.
the quotient
A dimensionless measure of density, the specific gravity , is the ratio of the density of an object or substance (labeled X)
X
water
Source: Undetermined
Collisions of particles (molecules or atoms) within a gas or liquid generate a force against a surface that is in contact with it. Fun Facts about air molecules: (77% nitrogen, 21% oxygen, 1-2%water, 1% other)
Gravity is the ultimate cause of hydrostatic pressure. Hydrostatic refers to non-accelerating fluids, particularly fluids at rest. Just as a stack of bricks must be strong enough to support its own weight, so the pressure in a fluid must vary with depth, so that the fluid below can support the weight of the fluid above.
pressure is increased from the surface value by an amount
What we measure as atmospheric pressure is merely the weight per unit area of the column of atmosphere extending upward from the Earth’s surface. It is often quoted in terms of the equivalent height of a column of mercury (specific gravity =13.6)
For a description of historical experiments on pressure and fluids, see http://galileo.imss.firenze.it/vuoto/eesper.html Otto von Guericke completed, around 1655, a pump which could extract the air from air-tight containers. With this new instrument, von Guericke was able to perform, at Magdeburg, in 1657, a spectacular experiment with the aid of a large number of his townsfolk. He demonstrated that the weight of air pushed together two perfectly sealed hemispheres, which had a vacuum created between them by the pneumatic pump, with such force that it needed two teams of 16 horses to separate them. Von Guericke understood that the weight of air was a force which could be put to work, to lift weights, for example. He thus initiated a line of research which led to the steam engine of James Watt (1736-1819) Source: Gaspar Schott, Mechanica hydraulico-pneumatica, Würzburg 1657
This concept is the basic operating principle of all hydraulic equipment. An external pressure applied to a fluid within a closed container is transmitted undiminished throughout the entire fluid. CC: BY-NC timailius (flickr) http://creativecommons.org/licenses/by-nc/2.0/deed.en CC: BY-NC-SA s__I (flickr) http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en
A small section within a fluid feels a higher pressure on its bottom than on its top. This difference in pressure produces an upward bouyant force
b
f
( m f is the mass of the displaced fluid) The magnitude of the buoyant force depends only on the mass of displaced fluid m f and is independent of the object’s geometry.
b directed against gravity with magnitude equal to the weight of the fluid displaced by the object.
You sit in a boat on a man-made lake filled with a fixed volume of water. Accompanying you is the pair of large rocks from the momentum chapter. This time, instead of throwing the rocks sideways, you drop them over the side and let them sink into the water. What happens to the water level of the lake after the rocks have sunk to the bottom?
