The electron is released from rest once it is 1 m from the proton, and travels back towards it. assuming that the proton remains stationary and the electric force is the only force acting, determine the speed of the electron when it has reached a distance of 5×102%% m from the origin.

An air-filled capacitor is formed from two long conducting cylindrical shells that are coaxial and have radii of 26 mm and 103 mm. the electric potential of the inner conductor with respect to the outer conductor is - 700 v (k = 1/4πε 0 = 8.99 × 109 n · m2/c2) the energy stored in a 1.0-m length of this capacitor is closest to