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Condensers - A Series Of Lectures And Articles Upon The Subject (Paperback) Loot Price: R118
Discovery Miles 1 180

# Condensers - A Series Of Lectures And Articles Upon The Subject (Paperback)

## F. R. Low

Loot Price R118 Discovery Miles 1 180

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CONDENSERS. BY F. R. If you build up a solid column of bricks the pressure which it exerts on its base will increase directly as the height of the column. A column ten feet in height will press twice as hard on its base as a column five feet high, and a column 100 feet high ten times as hard as a lo-foot column. Now, the point I want to make is that the pressure per square inch of base depends altogether on the height and not on the width or diameter of the column. A column 2 feet square will, it is true, press on its base with four times the pressure of a column one foot square and of the same height, because there are four times as many bricks in it and it weighs four times as much, but there is also four times as much base to it, so that the pressure per square inch of base is entirely independent of the cross section and depends upon the height alone. The same thing is true of water. A cubic foot of fresh water weighs 62.355 pounds at 62 degrees Fahrenheit. It is easy to remember this weight approximately, for it is the same as the de- with water. A grees and 62 is a standard temperature in dealing cubic foot restson a base of 144 square inches and is a foot high, so that the pressure per square inch on the base would be 62-355 -- 144 -433 of a pound and for every foot in height that we build our column or fill our pipe with water we gain 0.433 f a pound pressure per square inch. If one foot or 12 inches gives us 0.433 of apound it would take a column 12 -f- .433 27.71 inches in height to exert a pressure of one pound per square inch. For 82964 Fluid Pressure is Dependent upon Height of Column. every 27.71 inches in vertical height between the point at which you are measuringand thetop of a column of still water there will be a pressure of a pound to the square inch, and it makes no dif- ference whether you are measuring the pressure at the bottom of a one-eighth inch pipe, a twenty foot stand-pipe, or a lake, or the ocean itself. Every once in a while we have to explain this to the man who believes it takes more power to feed into the bottom of a tank than into the top, on account of the weight of water in the tank. The bottom of the tank holds up all the water except the column directly over the opening of the deliv- ery pipe, so that the additional pressure on the pump is due only to the depth of water in the tank, not to the size of the body, and it is impossible to feed into the top without increasing the height of the column fully as much. It makes no difference whether the height is due to the depth of the water inside the tank or an ad- ditional length of pipe outside. The difference between the water and the column of bricks is that while the pressure of the latter can act only vertically that of the water can act in all di- rections so that as you Fig. i lower a body into the water the pressure upon its surface in all directions increases one pound per square inch for every 27.71 inches of depth of water above it. In Fig. i, for instance, the pressure due to the column of waterPwill act upward upon the pistonA and sidewise upon the pistonsBand G as well as downward upon the piston D. We live at the bottom of an ocean of air. The winds are its currents, we can heat it, cool it, breathe and handle it, weigh it, and pump it as we would water. The depth of this atmospheric ocean cannot be determined as positively as could one of liquid, for the air iselastic and expands as the pressure decreases in the upper layers. It is variously estimated at from 30 to 212 miles...

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 Imprint: Read Books Country of origin: United Kingdom Release date: October 2007 First published: October 2007 Authors: F. R. Low Dimensions: 216 x 140 x 5mm (L x W x T) Format: Paperback - Trade Pages: 84 ISBN-13: 978-1-4067-8267-7 Categories: Books > Professional & Technical > Technology: general issues Books > Professional & Technical > Technology: general issues > Engineering: general LSN: 1-4067-8267-X Barcode: 9781406782677

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