A point charge 4.20 uC is held fixed at the origin. A second point charge 1.60uC with mass of 2.80×10-4kg is placed on the x axis, 0.280m from the origin.
A. What is the electric potential energy U of the pair of charges? (Take U to be zero when the charges have infinite separation.)
B.The second point charge is released from rest. What is its speed when its distance from the origin is 0.400m .
C.What is its speed when its distance from the origin is 4.00m.
D.What is its speed when its distance from the origin is 40.0 m.