Question

Два разноименных точечных заряда:-3нКЛ и +5нКл расположены на расстоянии 10 см.Какую работу надо совершить, чтобы увеличить расстояние в 3 раза?

Answer 1

$A = \frac{kq_{1}q_{2}}{r_{1}} - \frac{kq_{1}q_{2}}{r_{2}}$
Т.к. $r_{2} = 3r_{1}$ получим, что
$A = kq_{1}q_{2}( \frac{1}{r_{1}} - \frac{1}{3r_{1}})$
Подставив и посчитав, получим, что
$A = -13,8*10^{-40}$ Дж

Answer 2

Calculation of Work to Increase the Distance

To calculate the work required to increase the distance between two point charges, we need to consider the electric potential energy. The electric potential energy between two point charges is given by the formula:

U = k * (q1 * q2) / r

Where: - U is the electric potential energy - k is the Coulomb's constant (approximately 9 x 10^9 Nm^2/C^2) - q1 and q2 are the magnitudes of the two charges - r is the distance between the charges

In this case, we have two point charges: -3 nC and 5 nC, and the initial distance between them is 10 cm.

Let's calculate the initial electric potential energy using the given values:

U_initial = k * (q1 * q2) / r_initial

Substituting the values: - k = 9 x 10^9 Nm^2/C^2 - q1 = -3 nC = -3 x 10^-9 C - q2 = 5 nC = 5 x 10^-9 C - r_initial = 10 cm = 10 x 10^-2 m

U_initial = (9 x 10^9 Nm^2/C^2) * ((-3 x 10^-9 C) * (5 x 10^-9 C)) / (10 x 10^-2 m)

Now, we need to calculate the final distance, which is 3 times the initial distance:

r_final = 3 * r_initial

Substituting the value of r_initial:

r_final = 3 * (10 x 10^-2 m)

Finally, we can calculate the work required to increase the distance:

W = U_final - U_initial

Where: - U_final is the electric potential energy at the final distance

Let's calculate the work:

W = k * (q1 * q2) * (1/r_final - 1/r_initial)

Substituting the values: - k = 9 x 10^9 Nm^2/C^2 - q1 = -3 nC = -3 x 10^-9 C - q2 = 5 nC = 5 x 10^-9 C - r_initial = 10 cm = 10 x 10^-2 m - r_final = 3 * (10 x 10^-2 m)

W = (9 x 10^9 Nm^2/C^2) * ((-3 x 10^-9 C) * (5 x 10^-9 C)) * (1/(3 * (10 x 10^-2 m)) - 1/(10 x 10^-2 m))

Now, let's calculate the value of W using the given values.