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Homework Help: Thermo conversion question

  1. Jan 26, 2009 #1
    1. The problem statement, all variables and given/known data

    The problem asks to find the energy conversion efficiency of a blower-nozzle combination that produces a velocity of 30m/s for air with a density of 1.1kg/mcubed. The nozzle has a diameter of .15m

    input power is 1 hp

    2. Relevant equations

    given the flow rate = (density)(Area)(velocity)

    3. The attempt at a solution

    I know how to find the efficiency but do not know how to convert flow rate in (kg/s) to Power units in order to use (power out/power in) formula

    Thanks for your help!
  2. jcsd
  3. Jan 28, 2009 #2


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    Staff Emeritus
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    Can you figure out the volume of air that exits the nozzle in 1 second?

    And from that, can you use the velocity, and mass of that volume, to get it's kinetic energy?
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