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Velocity in angular motion.

  1. Jul 10, 2013 #1

    I was solving some problems today. Sometimes the wording is something like this:

    A ball attached to a string is traveling around a circular track with velocity [itex]4[/itex] m/s.

    When it says the velocity is 4 m/s , does this mean the tangential, or angular velocity?
    what is the distinction?

  2. jcsd
  3. Jul 10, 2013 #2


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    Angular velocity is not measured in m/s, but in 1/s.
  4. Jul 10, 2013 #3
    If you are doing uniform circular motion (beginner's physics), most likely the problem is talking about avg. speed. For example, if the circle has a circumference of 5 m and the ball traveled around it in 2 seconds, the avg. speed is 2.5 m/s.
  5. Jul 10, 2013 #4

    Yes, i'm doing beginners physics. I'm just having trouble finding if the object the problem mentions is traveling at a TANGENTIAL speed or ANGULAR speed. Like in the OP, how would you know that the velocity mentioned is tangential velocity?
  6. Jul 10, 2013 #5
    The speed Jewelia worked out is the tangential speed. For uniform circular motion, the tangential speed is constant (as well as the angular speed).

    Remember the relation between angular and tangential speeds: [itex] v = \omega r [/itex], so if it has units of [itex] m/s [/itex] it refers to the tangential speed.
    Last edited: Jul 10, 2013
  7. Jul 10, 2013 #6
    So does this mean whenever a problem says "an object moves with speed, s, in a circular path" the speed is the TANGENTIAL speed?I'm not sure how to phrase my question clearer.
  8. Jul 10, 2013 #7
  9. Jul 10, 2013 #8
    Look at your units. Most likely, the problem is referring to tangential speed.

    tangential speed is often written in meters/sec.

    angular speed has units of radians/sec or degrees/sec.
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