Select the correct answer.

The force of repulsion between two like-charged table tennis balls is [tex]$8.2 \times 10^{-7}$[/tex] newtons. If the charge on the two objects is [tex]$6.7 \times 10^{-9}$[/tex] coulombs each, what is the distance between the two charges? [tex]\left(k=9.0 \times 10^9 \ \text{newton meters}^2 / \text{coulomb}^2 \right)[/tex]

A. 0.32 meters
B. 0.70 meters
C. 6.7 meters
D. 8.2 meters



Answer :

Given:
- The force of repulsion between two like-charged objects [tex]\( F = 8.2 \times 10^{-7} \)[/tex] newtons.
- The charge on each object [tex]\( q_1 = q_2 = 6.7 \times 10^{-9} \)[/tex] coulombs.
- The electrostatic constant [tex]\( k = 9.0 \times 10^9 \)[/tex] Nm²/C².

To find: The distance [tex]\( r \)[/tex] between the two charges.

We use Coulomb's Law, which relates the force between two point charges to the distance between them:
[tex]\[ F = k \frac{q_1 q_2}{r^2} \][/tex]

We need to solve for [tex]\( r \)[/tex]. Rearranging the formula to isolate [tex]\( r \)[/tex]:
[tex]\[ r^2 = k \frac{q_1 q_2}{F} \][/tex]

Plugging in the values:
[tex]\[ r^2 = \frac{(9.0 \times 10^9) \times (6.7 \times 10^{-9}) \times (6.7 \times 10^{-9})}{8.2 \times 10^{-7}} \][/tex]

Evaluating the expression under the square root:
[tex]\[ r^2 \approx 0.49269512195121967 \][/tex]

Taking the square root of both sides to find [tex]\( r \)[/tex]:
[tex]\[ r \approx \sqrt{0.49269512195121967} \approx 0.7019224472484262 \, \text{meters} \][/tex]

Therefore, the distance between the two charges is approximately [tex]\( 0.70 \)[/tex] meters. The correct answer is:

B. 0.70 meters