# How close will body approach fixed point charge?

• Aleksandre
In summary, the problem involves a charged sphere with a mass of 15 mg and charge 2 nC moving towards a fixed point charge of 3 nC with a speed of 15 cm/s. The question asks for the distance at which the sphere will stop approaching the charge. To solve this, the equation for initial energy (1/2 * mv^2) is used, assuming an initial distance of infinity. This is then equated to the final energy equation (kQ1Q2 / x), where all values are known except for the distance x. This leads to a solution for x.
Aleksandre

## Homework Statement

Charged sphere with a mass of 15 mg and charge 2 nC moves with a speed of 15 cm/s towards a fixed point charge of 3 nC. How close will sphere approach charge?

K=(1/2)*mv2
U=k*(Q1Q2/r)

## The Attempt at a Solution

So I am not sure I approached correctly but that's all I could think of. As system initial energy = final energy I used formulae of kinetic energy and potential energy. At first, I assumed that initial distance was infinity. In that case, the initial energy in system would be expressed as :

Einitial=(1/2)*(mv2) = 1.6875 * 10-4 Joules

Then when the sphere reached to the point where electric field vector of point charge was so big that it had to stop, sphere stopped so v=0. That brings us to the Efinal equation:

Efinal=U=kQ1Q2/x
Here everything is known except x. So if we equate this equation to Einital we can find x distance easily. Also as units work out, I think this may be correct solution?

Aleksandre said:
I think this may be correct solution?
It is.

Aleksandre

## 1. How is the distance between two charged bodies related to the strength of their interaction?

The strength of the interaction between two charged bodies is inversely proportional to the square of the distance between them. This means that as the distance between the bodies decreases, the strength of the interaction increases.

## 2. How does the charge of a fixed point charge affect the distance at which it will interact with another body?

The charge of a fixed point charge does not directly affect the distance at which it will interact with another body. However, the strength of the interaction between two bodies is determined by the product of their charges, so a larger charge on the fixed point charge may result in a stronger interaction.

## 3. Can two fixed point charges approach each other indefinitely?

No, two fixed point charges cannot approach each other indefinitely. At a certain distance, the repulsive force between the charges will become stronger than the attractive force and they will repel each other.

## 4. Is the distance between two charged bodies the only factor that affects the strength of their interaction?

No, the distance between two charged bodies is not the only factor that affects the strength of their interaction. The type and magnitude of the charges also play a significant role in determining the strength of the interaction.

## 5. How can the distance between two charged bodies be calculated?

The distance between two charged bodies can be calculated using Coulomb's Law, which states that the force of interaction between two charged bodies is equal to the product of their charges divided by the square of the distance between them.

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