Could i get some help with this, thank you.

Question 1 The thin rod shown below has been bent into a perfect semicircle with radius R =16.0 cm. It carries a total charge of O = 2.50 nC. What is the electric potential at the center of the semicircle? _.-Ccnler Charge Q Question 2 .3; . -: ill) +++++++ +++++++ ||||I||||||||||| L A parallel-plate capacitor is formed of two 5.00 cm X 5.00 cm plates and spaced .t = 1.00 cm apart. The plates are charged to ::2.80 mil. If an electron is shot through a very small hole in the positive plate, as shown in the gure. What is the slowest speed the electron can have if it is to reach the negative plate? wartime