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

Perpetual Motion

  1. Jul 7, 2010 #1
    What do you call and where can i buy the set of balls (maybe 4 or 5) suspended in strings and when the outermost ball hits the the next one and bounces off the last one on the other end and sets off perpetual motion? I surely appreciate any ones response. Thank you. Josh
    Last edited by a moderator: Jul 7, 2010
  2. jcsd
  3. Jul 7, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Do a search on "Newton's Cradle" or "Newton's Balls".
  4. Jul 7, 2010 #3
    Hello justjoshus.You are describing "Newtons cradle" so try googling for suppliers.There is no such thing as perpetual motion and the balls in Newtons cradle stop eventually.
  5. Jul 7, 2010 #4


    User Avatar
    Science Advisor

    I wonder how long it'd go on in a vacuum. I'm guessing air resistance is by far the biggest source of losses.
    I'm guessing it'd go on for a surprising amount of time. Anyone got a high vacuum to try it out in?
  6. Jul 7, 2010 #5
    It would go on for longer in a vacuum but another major source of energy loss is due to the fact that during impact the balls get slightly distorted.
  7. Jul 7, 2010 #6
    Which generates heat and sound (which dissipates as heat).
  8. Aug 6, 2010 #7
    if magnets are involved in any mechanism of motion but it kept the motion consistant from other variables is it still considered perpetual motion??
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook