A plastic ball of charge -5 nC is held 2 cm above a glass bead of charge +5 nC at rest on a table.For the glass bead to leap up to the plastic ball its mass must be

Question

Quizplus · Accepted Answer

The force between the two charges can be calculated using Coulomb's law, $F = \frac{k \cdot |q_1 \cdot q_2|}{r^2}$, where $k$ is Coulomb's constant ($8.99 \times 10^9 \, \text{N m}^2/\text{C}^2$), $q_1$ and $q_2$ are the charges, and $r$ is the distance between them. For the glass bead to leap up, the electrostatic force must overcome the gravitational force acting on it, $F_g = m \cdot g$, where $m$ is the mass of the bead and $g$ is the acceleration due to gravity ($9.8 \, \text{m/s}^2$). Setting these forces equal and solving for $m$ gives the mass required for the bead to leap up. Given the specific numbers, the correct mass corresponds to the choice that correctly calculates this balance between electrostatic and gravitational forces.

A Plastic Ball of Charge -5 NC Is Held 2 μ\muμ

A Plastic Ball of Charge -5 NC Is Held 2 $\mu$