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 moves forward while the student holding balloon b stays in place, as modeled below. as a is moved closer, what happens to the strengths of the electric forces? - the electric force a exerts on b - the electric force b exerts on a related content electricity electric force magnetism magnetic force

Explanation:

To determine the effect of the distance between two charged objects on the electric force between them, we use Coulomb's Law. Coulomb's Law states that the magnitude of the electric force \( F \) between two point charges is directly proportional to the product of the magnitudes of the charges (\( q_1 \) and \( q_2 \)) and inversely proportional to the square of the distance (\( r \)) between them: \( F = k\frac{|q_1q_2|}{r^2} \), where \( k \) is Coulomb's constant.

In this problem, both balloons have a negative charge (they were rubbed with a blanket to give them a negative charge). When the student holding balloon A moves closer to balloon B, the distance \( r \) between the two balloons decreases.

1. Analyzing the electric force A exerts on B:

• According to Coulomb's Law, as the distance \( r \) between the two charges (balloons A and B) decreases, the denominator \( r^2 \) in the formula for the electric force becomes smaller.
• Since the force is inversely proportional to \( r^2 \), a smaller \( r^2 \) (because \( r \) is decreasing) will lead to a larger force. So, as A moves closer to B, the electric force A exerts on B gets stronger.

1. Analyzing the electric force B exerts on A:

• Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. In the context of electric forces, the force that A exerts on B is equal in magnitude and opposite in direction to the force that B exerts on A.
• Since the force A exerts on B gets stronger as the distance decreases, the force B exerts on A (which is equal in magnitude to the force A exerts on B) will also get stronger.

Answer:

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