What is the main difference between mass and weight?

The main difference between mass and weight lies in the definitions of each term and how they relate to gravity. Weight is the force exerted on an object due to gravity, which means it is dependent on both the mass of the object and the acceleration due to gravity acting on it. Specifically, weight can be calculated using the formula: Weight = Mass × Gravity. This means that as the strength of the gravitational field changes (such as on different planets), the weight of an object will also change, even if its mass remains constant.

In contrast, mass is a measure of the amount of matter in an object and does not change regardless of the object's location or the gravitational field it is in. Mass is an intrinsic property of matter, while weight is an extrinsic property that depends on external factors.

The other options either misrepresent the relationship between mass and weight or inaccurately define them. Hence, the distinction that weight includes the gravitational force acting upon a mass makes option B the correct understanding of the difference between these two key concepts in physics.