Select the correct answer.

Two balloons, one with a charge of [tex]\(4.0 \times 10^{-6}\)[/tex] coulombs and the other with a charge of [tex]\(8.2 \times 10^{-6}\)[/tex] coulombs, are kept 2.0 meters apart. What is the electric force between the two balloons? [tex]\((k = 9.0 \times 10^9 \, \text{N·m}^2/\text{C}^2)\)[/tex]

A. [tex]\(4.0 \times 10^9\)[/tex] newtons

B. [tex]\(5.2 \times 10^{-2}\)[/tex] newtons

C. [tex]\(7.3 \times 10^{-2}\)[/tex] newtons

D. [tex]\(8.2 \times 10^{-6}\)[/tex] newtons



Answer :

To determine the electric force between the two charged balloons, we can use Coulomb's law. Coulomb's law is given by the formula:

[tex]\[ F = k \frac{|q_1 \cdot q_2|}{r^2} \][/tex]

where:
- [tex]\( F \)[/tex] is the electric force between the charges,
- [tex]\( k \)[/tex] is Coulomb's constant, [tex]\( 9.0 \times 10^9 \, \text{newton-meter}^2 \text{coulomb}^{-2} \)[/tex],
- [tex]\( q_1 \)[/tex] and [tex]\( q_2 \)[/tex] are the charges on the balloons,
- [tex]\( r \)[/tex] is the distance between the charges.

Given:
- [tex]\( q_1 = 4.0 \times 10^{-6} \)[/tex] coulombs,
- [tex]\( q_2 = 8.2 \times 10^{-6} \)[/tex] coulombs,
- [tex]\( r = 2.0 \)[/tex] meters.

Let's substitute these values into Coulomb's law formula step-by-step to find the electric force:

1. Calculate the product of the charges:
[tex]\[ q_1 \cdot q_2 = (4.0 \times 10^{-6}) \cdot (8.2 \times 10^{-6}) \][/tex]
[tex]\[ = 32.8 \times 10^{-12} \, \text{coulombs}^2 \][/tex]

2. Calculate the square of the distance between the charges:
[tex]\[ r^2 = (2.0)^2 = 4.0 \, \text{meters}^2 \][/tex]

3. Now, apply Coulomb's law:
[tex]\[ F = k \frac{|q_1 \cdot q_2|}{r^2} \][/tex]
[tex]\[ F = 9.0 \times 10^9 \cdot \frac{32.8 \times 10^{-12}}{4.0} \][/tex]

4. Simplify the expression:
[tex]\[ F = 9.0 \times 10^9 \cdot 8.2 \times 10^{-12} \][/tex]

5. Multiply the constants:
[tex]\[ F = 73.8 \times 10^{-3} \, \text{newtons} \][/tex]

6. Convert the result to a simpler notation:
[tex]\[ F = 0.0738 \, \text{newtons} \][/tex]

Thus, the electric force between the two balloons is [tex]\( 0.0738 \)[/tex] newtons. Therefore, the correct answer is:

C. [tex]\( 7.3 \times 10^{-2} \)[/tex] newtons