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

Why does a stone tied to a string not fall?

  1. Sep 17, 2012 #1
    when we tie a stone to a string and spin it,it does not seem to fall.why does it happen?i mean to say that,no matter how great its horizontal velocity and centripetal force is,the vertical component of the acceleration wont be affected.it means that the stone should keep falling no matter how hard it is spun.why does it happen then?
     
  2. jcsd
  3. Sep 17, 2012 #2
    Here the falling force (gravitational) is being balanced by centripetal force. Hence do not fall.
     
  4. Sep 17, 2012 #3

    rcgldr

    User Avatar
    Homework Helper

    The string can never be completely horizontal, instead it's at some angle, and the vertical component of tension equals the weight of the stone (assuming steady state). It might be easier to understand this if you imagine that the stone is moving slowly, with the string nearly vertical, following the shape of a cone as the stone moves in a horizontal circle.
     
  5. Sep 18, 2012 #4
    rcgldr, you are right
    but, utkarsh5 is asking about
    when the stone is spinning in a horizontal circle why doesn't it fall, means what makes the stone to gain height.
     
  6. Sep 18, 2012 #5

    Doc Al

    User Avatar

    Staff: Mentor

    rcgldr gave the right answer. When the stone is making a horizontal circle, the string pulls at an angle, supporting the stone's weight as well as providing the centripetal force. The vertical acceleration of the stone is zero.
     
  7. Sep 18, 2012 #6
    thank you for your answers!now i understand the concept!thank you!!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook