What is the primary factor that causes weight?

Weight is defined as the force exerted on an object due to gravity, which is fundamentally a result of the attraction between masses. The primary factor that causes weight is the gravitational force, which acts between the mass of an object and the mass of the Earth (or other celestial bodies) that exerts this force. This gravitational attraction is directly proportional to the product of the two masses involved and inversely proportional to the square of the distance between their centers, as described by Newton's law of universal gravitation.

When we consider weight in a practical context, it is essential to understand that while an object's mass is a contributing factor, it alone does not dictate weight without considering the influence of gravitational force. Similarly, the distance from the Earth's center does affect weight, as gravitational attraction decreases with distance, but it does not solely define the concept of weight. Lastly, the speed of the object is unrelated to its weight; rather, weight concerns itself with the forces acting on the object rather than its state of motion.

Thus, the correct identification of weight as a result of the attraction between masses provides a clear and accurate understanding of why an object has weight in a gravitational field.