Kinetic Energy

Discussion in 'Bowhunting' started by telkev, May 16, 2008.

  1. telkev

    telkev Active Member

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    I have forgotten and lost the formula for finding kinetic energy, does anyone have it handy?
     
  2. Eaglet

    Eaglet Well-Known Member

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    KE=(1/2)mV²where m = mass of object
    v = speed of object
    ---------------------------------------------------------------
    For a bullet it goes like this:

    Formula used:
    Energy = 1/2* weight * velocity^2 / 7000 / 32.175

    Where weight is in grains, and velocity is in feet/second.

    7000 is grains per pound to convert the bullet weight
    into Lbs; and 32.175 is acceleration due to gravity.
    -----------------------------------------
    Or we can just say:

    Energy = weight * velocity^2 / 450450

    450450 comes from (7000*32.175*2)=450450
    ---------------------------------------------------
    Example:
    Bullet = 117 gr. MV=2900 ft/sec
    Energy = 2900*2900*117/450450 = 2184.4 ft/lbs
    ------------------------------------------------------------------------------------------------------------
     

  3. telkev

    telkev Active Member

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    Thanks, I feel stupid, I have used that formula so much in the past, I didn't even need a calculator. Guess I know which brain cells didn't make it.
     
  4. Eaglet

    Eaglet Well-Known Member

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    Telkev,
    don't mistreat yourself like that, I went to take an engineering test for a job, 3½ hours and in one of the question I needed the formula for a sphere's volume and I just could not remember it. And that I have used more than the KE formula.;) Starts happening after 40. LOL :D