In a case of a charged particle attracted to another fixed chrged particle both on one axis. force on charged particle will be F= (const)(q1*q2)/(r^2) for simplification = q1*q2*const =1 , and also mass of particle will be equal to one . so acceleration = 1/(r^2) r is distance between 2 particles, Another simplification is to assume r = X which is displacemnt of chrged particle(assuming fixed particle at fixed cordinates of(0,0,0) . so equation is accelration=1/(x^2) where x= velocity*time , velocity = initial velocity + acceleration *time. so how can i get displacment in variable of time ? Problem is that X is affected by v , v is affected by a , and a is affected by X. so its a loop.