Two surfaces in contact are moving slowly past each other. As the relative speed between the two surfaces in contact increases, what happens to the magnitude of their coefficient of kinetic friction

It begins to increase

Explanation:

As the surfaces move slowly and then increase their relative speeds, the coefficient of kinetic friction begins to increase until it reaches it terminal value in which, it can no longer increase.

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.