The correct option is **B. The electrostatic force can be both attractive and repulsive, while the gravitational force is always attractive.** ### Detailed Explanation: 1. **Understanding the Forces**: - **Electrostatic Force**: This force arises from the interaction between charged particles. According to Coulomb's Law, the electrostatic force \( F_e \) between two point charges \( q_1 \) and \( q_2 \) separated by a distance \( r \) is given by: \[ F_e = k \frac{|q_1 q_2|}{r^2} \] where \( k \) is Coulomb's constant (\( 8.99 \times 10^9 \, \text{N m}^2/\text{C}^2 \)). The force can be attractive (if the charges are of opposite signs) or repulsive (if the charges are of the same sign). - **Gravitational Force**: This force acts between two masses and is always attractive. According to Newton's Law of Universal Gravitation, the gravitational force \( F_g \) between two masses \( m_1 \) and \( m_2 \) separated by a distance \( r \) is given by: \[ F_g = G \frac{m_1 m_2}{r^2} \] where \( G \) is the gravitational constant (\( 6.674 \times 10^{-11} \, \text{N m}^2/\text{kg}^2 \)). This force can only pull masses together; it cannot push them apart. 2. **Why Option B is Correct**: - The key distinction here is that the electrostatic force can either attract or repel depending on the nature of the charges involved, while the gravitational force is always attractive due to the nature of mass. This fundamental difference is crucial in understanding how these forces operate in various physical scenarios. 3. **Why the Other Options are Incorrect**: - **Option A**: "The electrostatic force is always weaker than the gravitational force." - This statement is incorrect. In fact, the electrostatic force is generally much stronger than the gravitational force. For example, the electrostatic force between two electrons is about \( 10^{42} \) times stronger than the gravitational force between them. Thus, this option misrepresents the relative strengths of the two forces. - **Option C**: "The electrostatic force affects only charged particles, while the gravitational force affects all matter regardless of charge." - While it is true that the electrostatic force only acts on charged particles, the gravitational force does indeed affect all matter, but this option does not address the comparative nature of the forces. It does not highlight the unique characteristic of the electrostatic force being both attractive and repulsive, which is the essence of the question. - **Option D**: "Both forces decrease with distance, but the electrostatic force decreases at a slower rate than the gravitational force." - This statement is misleading. Both forces decrease with the square of the distance (\( r^2 \)), meaning they both follow an inverse square law. Therefore, they decrease at the same rate with distance, making this option incorrect. ### Summary: - The electrostatic force can be attractive or repulsive, while the gravitational force is always attractive. - The electrostatic force is generally much stronger than the gravitational force. - Both forces follow an inverse square law, decreasing with the square of the distance between the interacting bodies. - Understanding the nature of these forces is crucial for solving problems in physics related to charged particles and masses.