AP Physics C 2017

(Marvins-Underground-K-12) #1
Note: Please    be  careful with    your    signs   of  the potential   and electron    charge!

4 . C —The original force between the spheres is


When    the spheres are brought into    contact,    they    share   a   charge  until   they    have    the same    electric
potential:

In  addition,   we  know    that    Q 1  and    Q 2  must   add up  to  be  the total   original    charge  of  2Q:

Q   1    +  Q   2    =  2Q

Substituting,   we  get

Calculating the new electrostatic   force,  we  get the following:
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