Find the required force to hold a 4kg block against a wall which it's coefficient friction is 0.3.

An electron moving at 5.06 103 m/s in a 1.23 t magnetic field experiences a magnetic force of 1.40 10-16 n. what angle does the velocity of the electron make with the magnetic field? there are two answers between 0° and 180°. (enter your answers from smallest to largest.)