Question

a group of students has two balloons, labeled a and b. they rub the balloons with a blanket to give them negative (—) electric charge. then, the students hold the balloons a distance apart, as modeled below. the balloons exert electric forces on each other. next, the student holding balloon a stays in place while the student holding balloon b moves backward, as modeled below. as b is moved away, what happens to the strengths of the electric forces? - the electric force a exerts on b - the electric force b exerts on a options: stays the same, gets stronger, gets weaker

Explanation:

To determine the change in electric force strength, we use Coulomb's Law, which states that the electric force \( F \) between two charged objects is given by \( F = k\frac{q_1q_2}{r^2} \), where \( k \) is a constant, \( q_1 \) and \( q_2 \) are the charges of the objects, and \( r \) is the distance between them. In this case, both balloons have negative charges (so \( q_1 \) and \( q_2 \) are constant as the charge on the balloons doesn't change when moving them apart). As balloon B is moved backward, the distance \( r \) between the two balloons increases. Since the force is inversely proportional to the square of the distance (\( F \propto \frac{1}{r^2} \)), when \( r \) increases, the force \( F \) decreases. Also, by Newton's third law, the force A exerts on B is equal in magnitude and opposite in direction to the force B exerts on A. So both forces will decrease (get weaker) as the distance between them increases.

Answer:

• The electric force A exerts on B: gets weaker
• The electric force B exerts on A: gets weaker