How do you determine kinetic energy?

Two equal point charges Q are separated by a distance of d. One of the charges released and moves away from the other due only to the electrical force between them. When the moving charge is a distance 3d away from the other charge, what is the kinetic energy?

1 Answer
Jan 11, 2018

Initial potential energy of each of the charge is #Ep1=(1/K)(Q^2/d)#
When one of them is at a distance 3d from the other,its potential energy is #Ep2=(1/K)(Q^2/(3d))#
Therefore,this change in potential energy i.e
#(Ep1-Ep2)# has been converted to the kinetic energy of the moving charge i.e #(1/K)((2Q^2)/(3d))#