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Roational moment

  1. Jul 19, 2013 #1

    Ranger Mike

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    I need your help. I have a pivot point. On one side there is 95 pounds of resistance at 90 degrees to the lever. The lever is 18 inch long. on the other side of the pivot point I have a mass at the end of a 15.25” long lever. This mass wants to rotate clockwise about the pivot. The angle of intersection to the pivot is 12 degrees. The distance vertically between these two points is 5 inches.
    Doing the math 95 x 18 x 1 ( sine of 90 degrees) = 1710
    If I want the mass on the other side of the equation..I am getting confused by the 5 inch length. I know .208 is sine of 12 degrees.
    Do I add in the 5 inch to the calculation...??

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    Last edited: Jul 19, 2013
  2. jcsd
  3. Jul 19, 2013 #2

    Simon Bridge

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    Your sketch does not match the description.

    i.e. as drawn, assuming gravity acts "down", the mass wants to move anticlockwise.
    You have the 5" line vertical (OK) - which makes it the opposite side of a rt-angled triangle with a hypotenuse of 15.25" and an angle of 12deg. But this is not consistent since 15.25"sin(12)=3.17" i.e. there is no way the angle drawn is 12deg and the vertical distance is 5".
    Last edited: Jul 19, 2013
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