Question: A positive charge of 4.40 uC is fixed in place. From a distance of 4.20 cm a from the fixed positive charge, a particle of mass 5.20 g and charge +3.30 uC is released from rest.
A- What is the speed of the +3.30 uC when it is 7.10 cm away from the fixed positive charge?
I know the correct answer but explain how to get this answer!