1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Time for a ball on string to travel around a pole.

  1. Oct 17, 2012 #1

    Nny

    User Avatar

    1. The problem statement, all variables and given/known data

    A tetherball with a string length of 1.5m is hit in such a way that it completes a circle around the pole with the string at 30 degrees from the pole. Assuming it doesn’t lose a significant length during the trip around the pole and hence takes a perfectly circular orbit, what is the time period for a circuit around the pole for the ball? (Remember the acceleration caused by the string has to have a y component such that it completely counteracts the gravity).



    2. Relevant equations

    c=2pir //for the circumferences of the sircle it travels.
    xsinθ // distance from the pole to the ball, x direction only
    ycosθ // distance from the ball to the top of the pole, y direction only

    3. The attempt at a solution

    I really only got what I have listed above.
    x=0.75m , y≈1.299m , c≈4.7124m
    I assume I'd need to figure out the force of the hit to keep it that far out from the pole, then calculate time from that, but I'm drawing a blank right now.
     
  2. jcsd
  3. Oct 17, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Apply Newton's 2nd law. What forces act on the ball? What do you know about acceleration and circular motion?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook