Question

Знатоки физики,помогите пожалуйста! Я в растерянности... Задача:На шелковой нити висят два положительно заряженных шарика массой 40mг. Заряд одного шарика 10 нКл (нанокулон). Расстояние между ними 5 см. Чему равняется сила натяжения нити? Как изменится ответ, если изменить заряд шарика на противоположный?

Answer 1

Problem Analysis

To solve this problem, we need to calculate the tension force in the silk thread due to the two positively charged spheres. The tension force is the force exerted by the thread to keep the spheres in equilibrium. We can use Coulomb's law to calculate the electrostatic force between the spheres and then equate it to the tension force.

Calculation of Tension Force

The tension force in the silk thread is equal to the electrostatic force between the two spheres. Coulomb's law states that the electrostatic force between two charged objects is given by the equation:

F = k * (q1 * q2) / r^2

Where: - F is the electrostatic force between the spheres, - k is the electrostatic constant (k = 9 * 10^9 Nm^2/C^2), - q1 and q2 are the charges on the spheres, - r is the distance between the centers of the spheres.

In this problem, the charges on the spheres are both positive and equal to 10 nC (nanocoulombs), and the distance between the spheres is 5 cm.

Substituting the given values into the equation, we can calculate the electrostatic force between the spheres:

F = (9 * 10^9 Nm^2/C^2) * (10 * 10^-9 C) * (10 * 10^-9 C) / (0.05 m)^2

Simplifying the equation:

F = (9 * 10^9 Nm^2/C^2) * (10 * 10^-9 C)^2 / (0.05 m)^2

Calculating the value:

F = 180 N

Therefore, the tension force in the silk thread is 180 N.

Changing the Charge on the Sphere

If we change the charge on one of the spheres to the opposite sign (negative), the electrostatic force between the spheres will change direction. This means that the tension force in the silk thread will also change direction. The magnitude of the tension force will remain the same, as it depends on the magnitude of the charges and the distance between the spheres, which remain unchanged.

In summary, if we change the charge on one of the spheres to the opposite sign, the tension force in the silk thread will change direction, but its magnitude will remain the same.

I hope this helps! Let me know if you have any further questions.