Physics Electricity Question (stupid mistake?)?

Question

Ok Im new to electricity with physics and I cant figure out what I did wrong.

A particle of mass 60 g and charge 20 uC released from rest when its 60 cm from a particle of charge -15 uC
What is the magnitude of initial acceleration of the 64 g particle? (m/s^2)

OK a = kqq/(mass * r^2)

So (2.0e-5 * -1.5e-5 * 8.99e9)/(.064kg * .60^2) = -102.88

Just came to a revalation is this really the equation
a = kqq/r^2 * mass?
with an answer of -.479

Answer 1

force = k*|q1|*|q2|/r^2 (see ref.)
accel=force/mass, so your 1st equation is correct (except for lack of absolute values which make the force & accel positive). Something's fishy about your arithmetic; I get 117.06.