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Calculating how many surplus electrons on each sphere

  1. Jan 11, 2017 #1
    1. The problem statement, all variables and given/known data

    Two identical 9.60-g metal spheres (small enough to be treated as particles) are hung from separate 500-mm strings attached to the same nail in a ceiling. Surplus electrons are added to each sphere, and then the spheres are brought into contact with each other and released. Their equilibrium position is such that each string makes a 15.0 ∘ angle with the vertical

    How many surplus electrons are on each sphere?

    2. Relevant equations
    e= -1.602*10^(-19)

    3. The attempt at a solution

    I first began by converting all numbers to SI units

    Then I found the distance between the 2 balls (not sure)

    charge, I was not sure how to get this to use coulomb so I took the total mass .0096kg/(1.7*10^(-27))= an N

    N/2= number of electrons in each ball

    And I got lost here.

    I do not know how to find charge of objects in this scenario. All I know is they are the same charge because there are repelling
  2. jcsd
  3. Jan 11, 2017 #2


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    Each is at 15 degrees to the vertical. Draw the diagram, and mark the forces acting.
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