Okay First qusetion...

A proton is placed in an electrical field that counters the effect of gravity at sea level. Find The Electric Field.

Second Question...

A Proton is accelerated from rest in an electric field of 500.0 N/C. Find the velocity and kinetic energy of the proton at 3.00x10^-5s.

And Last Problem....

Three +1.00 uC charges are placed in the corners of a rectangle. height 2cm and width 10cm. Find the electric field at the forth unoccupied corner.

Thanks for your help....!