The correct option is **B**: Mass is a scalar quantity that measures the amount of matter in an object, while weight is a vector quantity that represents the gravitational force acting on that mass. ### Detailed Explanation 1. **Understanding Mass**: - **Definition**: Mass is a measure of the amount of matter in an object. It is a scalar quantity, which means it has magnitude but no direction. - **Units**: The standard unit of mass in the International System of Units (SI) is the kilogram (kg). - **Invariance**: Mass does not change regardless of the object's location in the universe. Whether you are on Earth, the Moon, or in space, the mass of an object remains constant. 2. **Understanding Weight**: - **Definition**: Weight is the force exerted on an object due to gravity. It is a vector quantity, which means it has both magnitude and direction (the direction is towards the center of the gravitational body, like Earth). - **Formula**: The weight (W) of an object can be calculated using the formula: \[ W = m \cdot g \] where \( m \) is the mass of the object and \( g \) is the acceleration due to gravity (approximately \( 9.81 \, \text{m/s}^2 \) on Earth). - **Dependence on Location**: Weight varies depending on the gravitational field strength. For example, an object weighs less on the Moon than on Earth because the Moon's gravitational pull is weaker. 3. **Why Option B is Correct**: - Option B accurately describes the fundamental difference between mass and weight. It highlights that mass is a scalar quantity related to the amount of matter, while weight is a vector quantity that depends on the gravitational force acting on that mass. ### Why the Other Options are Incorrect - **Option A**: "Mass is the force exerted by gravity on an object, while weight is a measure of the amount of matter in an object." - **Incorrect**: This statement reverses the definitions of mass and weight. Mass is not a force; it is the measure of matter. Weight is the force due to gravity. - **Option C**: "Mass and weight are interchangeable terms that both refer to the amount of matter in an object." - **Incorrect**: Mass and weight are not interchangeable. They refer to different physical concepts. Mass is a measure of matter, while weight is a force due to gravity. - **Option D**: "Mass decreases as an object moves away from the Earth, while weight remains constant regardless of location." - **Incorrect**: This statement is false because mass does not change with location. Weight does change with distance from the Earth due to the variation in gravitational force. ### Common Pitfalls - Confusing mass with weight is a common mistake. Remember that mass is a measure of matter and does not change, while weight is a force that can vary based on location. - Forgetting the units: Always use kilograms for mass and newtons for weight to avoid confusion. - Not considering the effect of gravity when calculating weight in different locations (e.g., on different planets or celestial bodies). ### Revision Summary - **Mass**: Scalar quantity measuring the amount of matter; constant regardless of location. - **Weight**: Vector quantity representing gravitational force on an object; varies with location. - **Formula for Weight**: \( W = m \cdot g \) (where \( g \) changes with location). - **Key Distinction**: Mass is about matter; weight is about gravitational force.