Can someone please help me with some questions please?? Thanks :)?

Question

Ok out of all of the questions I'm working on I have figured out all but these three they are giving me some trouble.



Question 1: Two identical brass balls mounted on wooden posts initially have different types of charge, +3uC and the other +15uC. The ball are allowed t touch and then are seperated again. What is the final charge on each ball?


Question 2: Two positive charges, each of magnitude 4 X 10 to the power of -6 C, are located a distance of 10cm from each other. What is the magnitude of the force exerted on each charge?


Question 3:An electron and a proton have charges of an equal magnitude but opposite sign of 1.6 x 10 to the power of -19 C. If the electron and a proton in a hydrogen atom are seperated by a distance of 5 x 10 to the power of -11 m, what are the magnitude and direction of the electrostatic force exerted on the electron by the protron?

Answer 1

(1) When the balls touch, the charge is uniformly distributed across them. When they separate, each has half:

( 3 uC + 15 uC ) / 2

(2) The force exerted on one charge by another is described by Coulomb's Law:

F = k q1 q2 / r^2

where k is the Coulomb constant, q1 and q2 the magnitude of the two charges, and r their separation. In this case, the forces have the same magnitude and opposite directions.

(3) Use Coulomb's Law as described above.