intro chapter 02.ppt

# intro chapter 02.ppt - CHAPTER 2 - THERMODYNAMICS Energy,...

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CHAPTER 2 - THERMODYNAMICS Force - A push or a pull – A vector quantity that accelerates a body in a direction of application – Applied to a stationary object to put it in motion – Applied to a moving object to keep it in motion – Applied to a stationary object to keep it stationary – Forces occur in pairs – A force is matched by an equal and opposite force – Measured in pounds, tons, Newtons Weight – An object’s mass * gravity W = m * g W = weight , lbs or kg m = mass , lbs or newtons g = gravity , 1.0 ft s 2 , 9.81 m s 2

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Pressure Pressure: Force per unit area: A force acting over an area psi, kpa Head Pressure – Inches of Water or Inches of Mercury – The pressure exerted by a column of liquid of a given height Atmospheric Pressure – Pressure exerted by the weight of the atmosphere – 14.7 psia, 760 millimeters (29.92 inches) of Hg Gage Pressure = Atmospheric Pressure - 14.7 (psig) Vacuum - Any pressure below atmospheric pressure Absolute pressure scale, psia. 0 psia = perfect vacuum Gage pressure scale, psig. 0 psig = 14.7 psia. A vacuum exists between 0.0 psig and - 14.7 psig. Vacuum gage, psi. Reads from 0 psig to 14.7 psi vacuum (0 psia) Mercury Scale, in Hg . A perfect vacuum will “pull” a column of Hg 29.97 inches high. Thus, 0.0” Hg = 0 psig; 29.97” Hg = 0 psia

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## This note was uploaded on 04/09/2008 for the course MT MT taught by Professor Gillis during the Spring '08 term at Mass Maritime.

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intro chapter 02.ppt - CHAPTER 2 - THERMODYNAMICS Energy,...

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