• jperk980
In summary, using the equation w=k*q1q2/r and r = (1/r1-1/r2), the expression for the work W that must be done to increase the radius of the circle of motion from r1 to r2 is (Qq/8pi*episolon_0)(1/r1-1/r2). This includes the calculation of potential energy (PE) as part of the total energy (TE = KE + PE). Further calculations are needed to determine the value of k, which is required to solve for the work W.
jperk980
A particle of positive charge Q is fixed at point P. A second particle of mass m and negative charge -q moves at constant speed in a circle of radius r1, centered at P. Derive an expression for the work W that must be done by an external agent on the second particle to increase the radius of the circle of motion to r2. (Use epsilon_0 for 0, r1 for r1, r2 for r2, and Q, m, and q as necessary.)
I know the answer to be (Qq/8pi*episolon_0)(1/r1-1/r2)
I know that i use the equation w=k*q1q2/r and i believe r to be (1/r1-1/r2). I do not understand how to get 8 though could someone please help!

TE= KE+PE
you forgot calculate the PE
increase the radius = change of TE

jperk980 said:
I know that i use the equation w=k*q1q2/r and i believe r to be (1/r1-1/r2). I do not understand how to get 8 though could someone please help!

Show your calculations briefly so that we can take it up from there.

## 1. What is electric potential energy?

Electric potential energy is the energy that is stored in an electric field due to the positions and charges of objects within that field. It is a type of potential energy that is associated with the interactions between electrically charged particles.

## 2. How is electric potential energy related to electric potential?

Electric potential energy is directly related to electric potential, which is a measure of the potential energy per unit charge at a certain point in an electric field. Essentially, electric potential energy is the amount of work that would be required to move a unit of charge from one point to another within an electric field.

## 3. What factors affect the amount of electric potential energy?

The amount of electric potential energy is affected by the magnitude of the electric charges involved, the distance between them, and the dielectric constant of the medium between them. Inversely, the amount of electric potential energy decreases as the distance between the charges increases.

## 4. How is electric potential energy measured?

The SI unit for electric potential energy is joules (J). It can be measured using the equation U = qV, where U is electric potential energy, q is the charge in coulombs (C), and V is the electric potential in volts (V).

## 5. What are some real-life examples of electric potential energy?

There are many examples of electric potential energy in our daily lives, such as the energy stored in a battery, a charged capacitor, or a lightning bolt. It is also present in the electrical systems of our homes, cars, and electronic devices. Hydroelectric power plants also harness the potential energy of water stored at a higher elevation to generate electricity.

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