The correct option is **B. Gravitational forces depend on the mass of the objects, whereas electrostatic forces depend on the charge of the objects.** ### Detailed Explanation 1. **Understanding the Forces**: - **Gravitational Force**: This is the force of attraction between two masses. It is described by Newton's Law of Universal Gravitation, which states that every point mass attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. The formula is: \[ F_g = G \frac{m_1 m_2}{r^2} \] where \( F_g \) is the gravitational force, \( G \) is the gravitational constant, \( m_1 \) and \( m_2 \) are the masses of the objects, and \( r \) is the distance between their centers. - **Electrostatic Force**: This is the force between charged objects. It can be either attractive or repulsive, depending on the types of charges involved (like charges repel, unlike charges attract). This force is described by Coulomb's Law: \[ F_e = k \frac{|q_1 q_2|}{r^2} \] where \( F_e \) is the electrostatic force, \( k \) is Coulomb's constant, \( q_1 \) and \( q_2 \) are the magnitudes of the charges, and \( r \) is the distance between the charges. 2. **Why Option B is Correct**: - Gravitational forces are indeed dependent on mass. The more massive the objects, the stronger the gravitational attraction between them. In contrast, electrostatic forces depend on the charge of the objects. The greater the charge, the stronger the electrostatic force. This fundamental difference in what each force depends on (mass for gravity and charge for electrostatics) makes option B the correct choice. ### Why the Other Options are Incorrect - **Option A**: "Electrostatic forces are always attractive, while gravitational forces can be both attractive and repulsive." - This statement is incorrect because electrostatic forces can be both attractive and repulsive. Like charges repel each other, while opposite charges attract. Gravitational forces, on the other hand, are always attractive; there are no repulsive gravitational forces. - **Option C**: "Electrostatic forces operate over much larger distances than gravitational forces." - This is misleading. Gravitational forces, while weak, can act over very large distances (like between planets and stars). Electrostatic forces, while they can also act over distances, tend to diminish quickly with distance due to the inverse square law. In practical terms, gravitational forces can be significant over astronomical distances, while electrostatic forces are usually significant only at much smaller scales. - **Option D**: "Gravitational forces are significantly stronger than electrostatic forces at the atomic level." - This statement is incorrect. In fact, electrostatic forces are much stronger than gravitational forces at the atomic level. For example, the electrostatic force between two protons is about \(10^{36}\) times stronger than the gravitational force between them. This is why atomic and molecular interactions are primarily governed by electrostatic forces rather than gravitational forces. ### Summary for Revision - Gravitational forces depend on mass, while electrostatic forces depend on charge. - Gravitational forces are always attractive; electrostatic forces can be attractive or repulsive. - Electrostatic forces are much stronger than gravitational forces at the atomic level. - Both forces follow an inverse square law, but their strengths and the nature of their interactions differ significantly.