# Determine the Charge on a Particle

## Homework Statement

a.) Two equally charged particles, held 22.4 cm apart, are released from rest. The initial acceleration of the first particle is observed to be 4.0 m/s2 and that of the second particle is 6.0 m/s2. If the mass of the first particle is 3.40 x 10-7 kg, determine the mass of the second particle in kg.

b.)For the previous problem, determine the charge on the particles?

## Homework Equations

F = ma, m = f/a, e = 1.609 x 10^-19

## The Attempt at a Solution

I am able to determine the mass of the second particle which is 2.26 x 10^-7. The second question states that we should find the charge on the particles. I tried to multiply the mass of the second particle by 1.609 x 10^-19. But i dont think that is the right formular because the unit does not cancel. Pls, is there any formula for charge?

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rock.freak667
Homework Helper
From part a you have the force F. So for part b, you will have to apply Coulomb's Law.

From part a you have the force F. So for part b, you will have to apply Coulomb's Law.
The SI unit of the answer is in Couloumbs (C) mean while the SI unit of coulombs law formular is N.kg^2/C^2.

rock.freak667
Homework Helper
The SI unit of the answer is in Couloumbs (C) mean while the SI unit of coulombs law formular is N.kg^2/C^2.
Coulomb's law describes the force between two electrostatic particles. You have the force from the first part, you just need to rearrange to get the correct quantity.

Coulomb's law describes the force between two electrostatic particles. You have the force from the first part, you just need to rearrange to get the correct quantity.
Hi,
I dont really understand what you mean by rearrange to ge the correct quantity..

rock.freak667
Homework Helper
Hi,
I dont really understand what you mean by rearrange to ge the correct quantity..
If your formula is something like

F=kM/r

you can rearrange to get M such that

M=Fr/k

What is the formula for Coulomb's law?

F= kq1q2/r2 (Coulombs law formular)

rock.freak667
Homework Helper
F= kq1q2/r2 (Coulombs law formular)

Since the charges are equal, what does that mean for q1 and q2?

It means that q1 and q2 have thesame charge and therefore they will repel each other. As we know, like charges repel and unlike charges attract.

rock.freak667
Homework Helper
It means that q1 and q2 have thesame charge and therefore they will repel each other. As we know, like charges repel and unlike charges attract.
Right so q1=q2, which means you can replace this by q2. So in F=kq2/r just rearrange to solve for q.