clear
//Given
m=9*10**-31// mass of e kg
V=10**6// velocity of e m/s
q=1.6*10**-19// charge of e C
a=9*10**9// constant

//Calculation
K=m*V**2// kinetic energy
r=a*q**2/K // Distance of the closest approach

//Result
printf("\n Distance of the closest approach is  %e  m", r)