Physics Two small spheres spaced 20.0 centimeters apart have equal charge. How many excess electrons

Physics
Two small spheres spaced 20.0 centimeters apart have equal charge. How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 4.57×10 -21 newtons?
Friday, January 24, 2014 at 4:57pm

Physics
How much charge is contained in 9kg of protons? Express your answer to two significant figures and include the appropriate units.
Friday, January 24, 2014 at 4:56pm