Center of gravity for a two dimensional body is the point at which the entire _____ acts regardless of the orientation of the body.

• A. Weight
• B. Mass
• C. Mass or Weight
• D. Volume

Answer: (A)

The main idea here is that the center of gravity is the point at which the total gravitational force on the body can be considered to act. In a uniform gravitational field, all parts of the body experience gravity, and the vector sum of those forces—the weight—acts as if it were concentrated at a single point. That single point is the center of gravity. This is why tilting or reorienting the body doesn’t change where the weight effectively acts, as long as gravity is uniform. Mass is a property distributed throughout the body, and volume is just a measure of space, neither of which pinpoints where the gravitational pull acts. Therefore, the correct choice is weight.