# Physics problem on force of a charge

• Joshua Beyer
In summary, the two point charges on the x-axis, one with a charge of +10nC located at the origin and the other with a charge of -18nC located at x = 9.0m, create a force on each other according to Coulomb's law with a constant of 9.0*10^9. The force on q2 is 1.3122*10^14 away from q1, while the force on q1 is in the opposite direction.
Joshua Beyer

## Homework Statement

Two point charges are on the x-axis. One charge, q1 = +10nC, is located at the origin, and the other charge, p2=-18nC is located at x = 9.0m

## Homework Equations

a.) what is the force on q2(include direction)?
b.) what is the force on q1(include direction)?

## The Attempt at a Solution

f=(k(q1q2)/r^2)
f=(9.0*10^9(10*18)/9^2)
K = coulomb's law = 9.0*10^9
I got 1.3122*10^14, but was told that was WAY wrong.

HI, Joshua. Welcome to PF!

(1) Note that the charge is given in units of nC. You need to take into account the "n".
It's a very good idea to include units in your calculation and make sure that the units combine to give the correct unit for the force.

(2) Looks like you multiplied by 9^2 rather than divided by 9^2.

(3) "k" is Coulomb's constant, not Coulomb's law.

Joshua Beyer said:

## Homework Statement

Two point charges are on the x-axis. One charge, q1 = +10nC, is located at the origin, and the other charge, p2=-18nC is located at x = 9.0m

## Homework Equations

a.) what is the force on q2(include direction)?
b.) what is the force on q1(include direction)?

## The Attempt at a Solution

f=(k(q1q2)/r^2)
f=(9.0*10^9(10*18)/9^2)
K = coulomb's law = 9.0*10^9
I got 1.3122*10^14, but was told that was WAY wrong.

I believe the "n" in "nC" stands for "nano".

## 1. What is the formula for calculating the force of a charge?

The formula for calculating the force of a charge is F = k * (q1 * q2)/r^2, where k is the Coulomb's constant, q1 and q2 are the charges of the two objects, and r is the distance between the two charges.

## 2. How does the distance between two charges affect the force between them?

The force between two charges is inversely proportional to the square of the distance between them. This means that as the distance increases, the force decreases and vice versa.

## 3. Can the force of a charge be repulsive or attractive?

Yes, the force of a charge can be either repulsive or attractive depending on the charges of the two objects. Like charges (both positive or both negative) will repel each other, while opposite charges (one positive and one negative) will attract each other.

## 4. How does the magnitude of the charges affect the force between them?

The force between two charges is directly proportional to the product of their magnitudes. This means that the larger the charges, the greater the force between them.

## 5. What is the unit of force for a charge?

The unit of force for a charge is Newtons (N). This is the same unit used for other types of forces, such as weight and friction.

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