A research Van de Graaff generator has a 3.90 m diameter metal sphere with a charge of 1.08 mC on it.

(b) At what distance from its center is the potential 2.00 MV?

(c) An oxygen atom with three missing electrons is released near the surface of the Van de Graaff generator. What is its kinetic energy in MeV at the distance determined in part (b)?

What do you need on

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other

Ithink it is a. but i'm not 100 percent sure.

The figure is missing but we can answer anyway.the correct answer is "releasing the string". in fact, when the person is holding the bow and the arrow, the kinetic energy of the arrow is still zero (because the arrow is not moving). the moment the arrow is released, it acquires a velocity v, so its kinetic energy will become different from zero: where m is the mass of the arrow and v its velocity.  all the other options, instead, do not increase the kinetic energy of the system: -  pulling farther back on the string : this will just increase the elastic potential energy of the system-  holding the arrow higher: this will increase the gravitational potential energy of the system (which is given by u=mgh, where h is the height above the ground)-  decreasing the mass of the arrow: this will decrease the gravitational potential energy of the system (which is given by u=mgh, where m is the mass)