Magnetic fields and motor principle

1) An electron moves at a speed of 5.0x10^6m/s perpedicular to a uniform magnetic field. The path of the electron is a circle of radius 1.0x10^-3m.

a)what is the magnitude of the magnetic field?

b)what is the magnitude of the electron's acceleraton in the field

2) A beam of protons move in a circle of radius 0.22m at right angles to a 0.35T magnetic field.

a)What is the speed of each proton?

b)what is the magnitude of the centripetal force acting on each proton.

Tried a few equations but still can't seem to get the right answers....