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

Homework Help: Charged Beads

  1. Mar 6, 2008 #1
    1. The problem statement, all variables and given/known data
    Two charged beads, Q1 and Q2, are placed on a long frictionless (insulating) rod. Initially they are very far apart; the bead Q2 is glued in place and does not move. Both beads have mass 10g and carry charge 2uC. Q1 is set in motion at a velocity v= 10 m/s towards Q2.

    A) How close does Q1 get to Q2 before reversing its direction of motion?

    B) What is the maximum force exerted on charge Q1?

    2. Relevant equations

    This is kinda how the diagram that goes with it looks like:


    In which the first asterix is Q1 -->
    and the second asterix is the fixed Q2

    3. The attempt at a solution

    I don't know where to start. Don't i need to know how far apart they are in order to find out how close Q1 will get? Ugh.
  2. jcsd
  3. Mar 6, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Perhaps you could use the principle of conservation of energy: consider the initial total energy (kinetic + potential) and set that equal to the total energy when the relative velocity is zero. The "very far apart" initial condition may simplify this expression.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook