Find the central force acting on the electron

Question

In the Bohr model of the hydrogen atom, the speed of the electron is approximately 2.19 × 106 m/s. Find the central force acting on the electron as it revolves in a circular orbit of radius 5.31 × 10−11 m. Answer in units of N.

Answer 1

a_c=v_t²/r where a_c is centripetal acceleration (m/s²), vt is tangential velocity (m/s) and r is the radius (m) of the "orbit" and F=ma, so F_c=m_ev_t²/r.  Note that if [m_e] = kg where [] means "units of", then we'll have [F_c] = [m_e][v_t]²/[r] = (kg)(m/sec)²/m = kg m / sec² = N.