1. Not finding help here? Sign up for a free 30min 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!

Ball and string

  1. Jun 24, 2004 #1
    I can't figure out how to do this one...please help!

    A 2.4kg ball tied to a string fixed to the ceiling is pulled to one side by a force F to an angle of 28 degrees from the ceiling. Just before the ball is released and allowed to swing back and forth, (a) how large is the force F that is holding the ball in position and (b) what is the tension in the string?

    I tried solving this using x and y components, but it's not working. How would I set this up using components?
     
  2. jcsd
  3. Jun 24, 2004 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Show what you've done. (I assume that the force F is meant to be a horizontal force.) Give the x and y components of each force acting on the ball.
     
  4. Jun 24, 2004 #3
    I know that tension from the string is acting on the ball, its weight*gravity, and the force that i'm trying to find, but with two unknowns, how do i find force and tension?
     
  5. Jun 25, 2004 #4
    I know what you're getting at. It seems rather puzzling doesn't it. If you just let F be a force with 0 as the vertical component, you should be able to solve this. My question is, if I don't know the direction of F, how do I solve this problem?
     
    Last edited: Jun 25, 2004
  6. Jun 25, 2004 #5

    Doc Al

    User Avatar

    Staff: Mentor

    Remember rule #1: Always do what Doc Al says! (Just kidding... :smile:) But I asked you to find the x and y components of each force acting on the ball. Do it! Then add the x components and set equal to zero; then do the same for the y components. You'll get two equations and two unknowns.
     
  7. Jun 25, 2004 #6

    Doc Al

    User Avatar

    Staff: Mentor

    The magnitudes of the force F and the tension depend on the angle that the force makes. So if you aren't given the direction of F, you don't have enough information.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Ball and string
  1. Ball on a String (Replies: 14)

  2. Ball on a String (Replies: 3)

  3. String and ball (Replies: 5)

  4. A ball on a string (Replies: 29)

Loading...