V=15+5t (m/s) vận tốc ban đầu có giá trị là

Could someone me find the answer to this problem.

Uppose we consider the system of the three capacitors as a single "equivalent" capacitor. given the charges of the three individual capacitors calculated in the previous part, find the total charge qtot for this equivalent capacitor. express your answer in terms of v and c.

What happens when a rubber rod is rubbed with a piece of fur?