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  • OT Need an equation

    Physics was a long time ago. Need the equation for the force in gees on a rotating object. As in say the classic wheel shaped space station.
    Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

  • #2
    I have the text books from my physics classes on the shelf and will
    look it up but it's something like mass times angular acceleration
    all in the right units. :-)
    Back to you in a bit.
    ...lew...

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    • #3
      This one is about as simple as it gets:

      http://aquaticpath.umd.edu/nomogram.html

      Phil

      Originally posted by Spin Doctor
      Physics was a long time ago. Need the equation for the force in gees on a rotating object. As in say the classic wheel shaped space station.

      Comment


      • #4
        The basic formula is: w^2 x R / gravity constant

        w = radians per second
        R= radius in meters or feet
        gravity constant is 9.81 m/sec^2 for metric and 32.2 in Imperial

        Using rpm, the formula is: (rpm x 2 x 3.1415 / 60)^2 x R / gravity constant

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        • #5
          That was the very first mainframe program I wrote in '67.

          Relative Centrifugal Force= 0.00001118*radius in cm*rpm^2

          or

          RCF=0.0000283972*radius in inches*rpm^2
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            OK. University Physics, Mechanics Heat and Sound by Sears and Zemansky. Chapter 6 , section 2 circular motion, and section 3, Centripetal force:
            It boils down to the velocity around the circle is: v = 2 pi R / T
            After a bunch of derivitives.
            the radial acceleration is: a = v squared / R
            Now everyone know force is mass time acceleration so :
            The radial force is the mass times the "speed" of the object going around the circle squared divided by the radius of rotation.
            The units of Force will be dependant on the units of mass and linear measure.

            Mass in grams and dimensions in cm = force in dynes.

            Remember that G's are not a unit of Force

            How much deeper do you want to go?
            ...lew...
            on edit I see it was a waste of time

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            • #7
              F=mrω²

              Where:
              F=Force
              m=mass
              r=distance of mass from center of rotation
              ω=rotational velocity in radians/second
              "The truth is incontrovertible, malice may attack it, ignorance may deride it, but in the end; there it is." Winston Churchill

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              • #8
                Weird, I never would of guessed its exponential with speed. I would of thought it would be linear.
                Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                • #9
                  Whirlybits x Speed divided by chucky off bits.
                  .

                  Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                  • #10
                    Originally posted by Black_Moons
                    Weird, I never would of guessed its exponential with speed. I would of thought it would be linear.
                    It's quadratic, not exponential.

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                    • #11
                      Yup

                      Originally posted by 3jaw
                      F=mrω²

                      Where:
                      F=Force
                      m=mass
                      r=distance of mass from center of rotation
                      ω=rotational velocity in radians/second
                      Yup.

                      http://en.wikipedia.org/wiki/Centripetal_force

                      Comment


                      • #12
                        If you ever get stuck on a basic, or even not-so-basic, concept in Physics go to the HyperPhysics website at Georgia State University. It has a very easy to navigate visual tree of concepts or you can just use the index. It even has built in calculators and graphers for most of the formulas.

                        Bookmark it.

                        -DU-

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                        • #13
                          That is one of the better ones that I use regularly. Another is Eric Weisstein's Wolfram Mathworld. If you need the formula for anything mathematical it is there.
                          Free software for calculating bolt circles and similar: Click Here

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