Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Circular motion question

  1. Sep 5, 2005 #1
    A tether ball of mass 0.5kg is attached to a vertical pole by a cord 1.5m long. Assume the cord attches to the centre of the ball. If the cord makes an angle of 20 degrees with the vertical, then:
    a) what is the tension in the cord?
    b) what is the speed of the ball?

    im having trouble with this question. im assuming that the ball is nearly at the top of its swing...just 20 degrees away from it...can anyone help me with part a)? im not sure if it has anything to do with centripetal force...
  2. jcsd
  3. Sep 5, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    You have misunderstood the situation:
    The tether ball moves in a circular orbit in the HORIZONTAL plane, to which the the vertical is the normal direction.

    In this situation, you will find that the speed of the ball and the tension in the cord are CONSTANTS throughout the circular motion.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook