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

B Paradox of centripetal force

  1. Nov 9, 2016 #1
    If we have a frictionless hollow tube and a ball which just fits into it. All the surfaces are frictionless.

    Now if we put in the ball about at the center of tube and rotate the tube about one of its ends with a constant angular velocity ,then the ball swoops out of
    the other end .

    If we see from the ground frame then no radial force is acting as friction is absent,then how can we explain the motion of the ball.According to Newton's first law we need a force to change the state of motion.

    How do we explain this
     
    Last edited: Nov 9, 2016
  2. jcsd
  3. Nov 9, 2016 #2

    A.T.

    User Avatar
    Science Advisor
    Gold Member

    Yes, the acceleration will be tangential only (perpendicular to the tube axis), which is not a constant direction in the ground frame.
     
    Last edited by a moderator: Nov 9, 2016
  4. Nov 9, 2016 #3

    jbriggs444

    User Avatar
    Science Advisor

    To expand a bit on what @A.T. has said, the acceleration which is applied now and is tangential now results in a velocity which is tangential now but which is retained and will have a radial component a moment from now when the "radial" and "tangential" directions change.
     
  5. Nov 26, 2016 #4
    hello mausam
    exactly , very reason why the ball pops out , cause theres no force acting inwards to keep its radius const.
    ball tries tries to move in one line . think of tangent to a circle , as you move along tangent,you move further away from circle centre
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Paradox of centripetal force
  1. Centripetal force (Replies: 11)

  2. Centripetal force . (Replies: 6)

  3. Centripetal Force (Replies: 9)

  4. Centripetal force (Replies: 7)

Loading...