Introduction to Physical Science Monday, Wednesday, Thursday Tom Burbine [e-mail]

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Introduction to Physical ScienceMonday,
Wednesday, ThursdayTom Burbinetomburbine_at_astr
o.umass.edu
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Quiz 3

• Projectile Motion
• Densities
• Pressure in a liquid
• Pressure in a gas

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• http//www.youtube.com/watch?veQsmq3Hu9HA

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Gases and Liquids

• Primary difference is the distance between
  molecules
• Gas Molecules are far apart
• Liquid Molecules are closer due to cohesive
  forces
• Density of air at 10 oC is 0.0012 g/cm3 or 1.2
  kg/m3

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• Air and liquids always flow from areas of high
  pressure to areas of low pressure

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Boyles Law

• Product of the pressure and the volume for a
  given mass of gas is a constant as long as the
  temperature does not change
• P1V1 P2V2

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Atmospheric Pressure

• Weight of air above you
• Average pressure at sea level is 101,300 Pascals
• This pressure is called one atmosphere

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Pascals Principle

• A change in pressure at any points in an enclosed
  fluid at rest is transmitted undiminished to all
  points in the fluid

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• P1 P2
• W1 W2

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Buoyancy in a gas

• An object surrounded by air is buoyed up by a
  force equal to the weight of the air displaced
• Archimedes Principle

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For example

• Cubic meter of air has a mass of 1.2 kg
• Weight is 11.76 Newtons
• Any object with a volume of 1 cubic meters is
  buoyed up with a force of 11.76 Newtons
• If it has a mass less than 1.2 kilograms, it
  floats
• If it has a mass greater than 1.2 kilograms, it
  sinks

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Bernoullis Principle

• When the speed of a fluid increases, internal
  pressure in the fluid decreases
• http//woodburygirl.edu.glogster.com/hydrostaticsv
  shydrodynamics/

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Any Questions?