### Correct Option: B **Explanation of the Correct Answer:** The gravitational field strength (often denoted as \( g \)) at a point in space is defined as the force experienced by a unit mass placed at that point in the gravitational field. This means that if you were to place a small mass (usually taken as 1 kg for simplicity) at that point, the gravitational field strength tells you how much force that mass would experience due to gravity. Mathematically, this can be expressed as: \[ g = \frac{F}{m} \] Where: - \( g \) is the gravitational field strength (in Newtons per kilogram, N/kg), - \( F \) is the gravitational force acting on the mass (in Newtons, N), - \( m \) is the mass of the object (in kilograms, kg). In a uniform gravitational field near the Earth's surface, the gravitational field strength is approximately \( 9.81 \, \text{N/kg} \). This means that a 1 kg mass would experience a force of about 9.81 N downward due to gravity. **Why the Other Options are Incorrect:** - **Option A: "It is the mass of an object divided by the force acting on it."** - This statement is incorrect because it reverses the relationship between mass and force. The gravitational field strength is not defined as mass divided by force. Instead, it is the force per unit mass. The correct relationship is \( g = \frac{F}{m} \), not \( g = \frac{m}{F} \). - **Option C: "It is the gravitational force between two masses divided by the distance between them."** - This option is misleading. While the gravitational force between two masses is given by Newton's law of gravitation as \( F = G \frac{m_1 m_2}{r^2} \) (where \( G \) is the gravitational constant and \( r \) is the distance between the centers of the two masses), this does not define gravitational field strength. Gravitational field strength is concerned with the force experienced by a unit mass at a point in the field, not the force between two masses. - **Option D: "It is the total mass of all objects in the vicinity divided by the square of the distance from the center of mass."** - This option is also incorrect. While it hints at the concept of gravitational attraction, it does not accurately describe gravitational field strength. The gravitational field strength at a point is not simply the total mass divided by the square of the distance; rather, it is the force per unit mass at that point. The correct formula for gravitational field strength due to a point mass is \( g = G \frac{M}{r^2} \), where \( M \) is the mass creating the field and \( r \) is the distance from the mass to the point in question. ### Summary of Key Points: - Gravitational field strength is defined as the force experienced by a unit mass at a point in the gravitational field. - It is mathematically expressed as \( g = \frac{F}{m} \). - The correct unit for gravitational field strength is Newtons per kilogram (N/kg). - Common misconceptions include confusing the definitions of force, mass, and their relationships in gravitational contexts. This understanding of gravitational field strength is crucial for solving problems related to gravity in physics, especially in mechanics and astrophysics.