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Homework Help: Rpm related to velocity and diameter

  1. Jun 10, 2010 #1
    How do you determine RPM when given your velocity and the radius or diameter of the cirlcle?

    thanks in advance.
  2. jcsd
  3. Jun 10, 2010 #2
    One circumference is 2Pi.r. That's distance travelled in one revolution.
    If you travel at speed v, then the time T it takes to travel that distance = distance divided by speed.
    Finally, if it takes T seconds for one revolution, you do 1/T revolutions per second.
    Put it all together to get the answer.
  4. Jun 10, 2010 #3
    so for r = 1.5 ft therefore 2pi(1.5) = 9.42 feet
    speed equals 95.34 ft/s

    T = distance/speed = 9.42 ft/ 95.34 ft per sec = .0988

    1/T = 1/.0988 = 10.121 rev/s

    IS this correct.
  5. Jun 10, 2010 #4
    Yes, that looks fine to me. :)
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