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How to Calculate Rotational Force

Updated March 23, 2017

Rotational force, also known as torque or centripetal force, is the measurement of the force of an object rotating around a central axis or pivot. For example, using a wrench to turn a bolt creates enough force to either tighten or remove the bolt. The force that is coming from turning the wrench is considered the rotational force that is being created. To find rotational force, a person must know the mass of the object creating the torque, the velocity that it is being moved, and the radius of how far away the object is from the axis.

Take the velocity of the object that is being turned to the second power. For example, if the velocity of the object is 15 meters per second, multiply 15 by 15 to get 225.

Multiply the mass of the object being used to create torque by the squared velocity. For example, if the mass of the object is 28 grams, that would mean you multiply 28 by 225 to get 6300.

Divide the answer from Step 2 by the radius that is measured from the centre of the axis to the object that is being used to create the rotational force. For example, if the radius is 19 meters, that would mean you divide 6300 by 19 to get 331.58 Newton meters. (Newton meters is the SI unit used for rotational force.) This is the rotational force that is being created.

Things You'll Need

  • Calculator
  • Mass of an object
  • Velocity of the rotation
  • Radius of the object from the axis
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About the Author

Rick Paulas is a freelance writer based out of Los Angeles. He has been writing professionally since 2005. He has previously written for "McSweeney's," ESPN.com, "Vice Magazine" and "Radar Magazine," and has worked as an editor for "The Coming," "Duct Tape & Rouge," and "TSB Magazine." Paulas holds a Bachelor of Arts in telecommunications and advertising from Michigan State University.