# Calculate the mass of particle 2

1. Jan 20, 2010

### shimizua

1. The problem statement, all variables and given/known data
Two point-like particles are placed a distance, d, apart and are
given equal and opposite charge. The ﬁrst particle, of mass m1, has
an initial acceleration of a1 toward the second particle.

a)Calculate the mass of particle two, m2, if it has an initial acceleration of a2.
b)What is the magnitude of the charge, q, on each particle?

2. Relevant equations
I am pretty sure I would be a=F/m
Coulombs law F=kq1q2/r^2

3. The attempt at a solution
So we arent supposed to actually have numbers to this, we just need to write like what equation we use and why we use it and stuff like that.
For part a, we would just use a=F/m (cant remember what the name of the equation is if you can help me with that too). but since we know what m1 and a1 are we use that to find F. Then we just use that F since it would be the same for both (at least I think) and we know what a2 is. so it would just be a2/F=m2. Right?
then for part b i am just not really sure. I know that we would want to use Coulomb's Law to find it. so F=kq1q2/r^2. but since we dont know either charge i am just confused

2. Jan 20, 2010

### tiny-tim

Hi shimizua!

(try using the X2 and X2 tags just above the Reply box )
That's good ol' Newton's second law … F = ma.
Right.
But you know q1 = -q2, and you've just found F.