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Homework Help: Question on speed

  1. Oct 9, 2005 #1
    Two tiny metal spheres A and B of mass 5g and 10g have equal positive charge q = 5 microCoulombs. The spheres are connected by a massless nonconducting string of length 1 m, which is much greater than the radii of the spheres. What is the electric potenial energy of the system? Suppose you cut the string. At that instant what is the acceleration of each sphere? A long time after you cut the string, what is the speed of each sphere?

    Ok the first two questions are easy, no problem, but I'm hesitating on the last one. I'm not sure what to do. Any hints?
  2. jcsd
  3. Oct 9, 2005 #2


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    Homework Helper

    What's the Electric PE "a long time" after cutting it?
    How could it be different than it was originally?
    Or are you forgetting momentum conservation?
  4. Oct 9, 2005 #3
    Got it. Thanks. What was I thinking.
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