A uniform electric field of magnitude 15.0 N/C is directed parallel to the positive x-direction. A proton is at the origin (x=0, y=0) at time t=0 when it is moving with a velocity of 5.0 x 10^4 m/s in the positive y-direction. Ignore and non-electric forces. At some particular later time, it has an x-coordinate of 4.0m.
a.) What is the potential difference between the final and initial positions? Did the potential increase or decrease?
b.) By how much did the potential energy of the proton change? Did it increase or decrease?
c.) What is the speed of the proton at the later time?