Calculate the mass of particle 2

[shimizua]

Homework Statement

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?

Homework Equations

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

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 don't know either charge i am just confused

 

[tiny-tim]

Hi shimizua!

(try using the X² and X₂ tags just above the Reply box )

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).

That's good ol' Newton's second law … F = ma.

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?

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 don't know either charge i am just confused

But you know q₁ = -q₂, and you've just found F.

 

[kerimek]

on how to go about this.


Yes, you are on the right track for part a. The equation you are using is Newton's Second Law, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. So, using the known values for m1 and a1, you can calculate the net force acting on particle 1 and then use that to find the mass of particle 2.

For part b, you are correct that you will need to use Coulomb's Law. Since the two particles have equal and opposite charges, the force between them will be equal and opposite as well. This means that the magnitude of the charges, q, will be the same for both particles. So, you can set up an equation using Coulomb's Law with the known values for the net force and the distance between the particles, and solve for q.