Define displacement.

Define displacement.

• A. Weight of the volume of water that the ship displaces when floating freely
• B. The force required to keep the ship afloat
• C. The length of the hull
• D. The total weight of the ship

Answer: (A)

Displacement comes from Archimedes’ principle: a floating hull pushes water aside, and the buoyant force acting upward equals the weight of that displaced water. For a vessel in equilibrium, its own weight is balanced by this buoyant force, so the weight of the ship equals the weight of the water it displaces. Therefore displacement is defined as the weight of the water displaced by the hull. That makes the correct description the statement about the weight of the volume of water displaced by the ship. The other ideas describe related concepts—how hard you must pull to keep it afloat, or a hull’s length, or the ship’s total weight—but they do not define displacement itself. (The ship’s total weight is numerically equal to displacement in weight for a floating vessel, but the definition centers on the water displaced.)

Displacement comes from Archimedes’ principle: a floating hull pushes water aside, and the buoyant force acting upward equals the weight of that displaced water. For a vessel in equilibrium, its own weight is balanced by this buoyant force, so the weight of the ship equals the weight of the water it displaces. Therefore displacement is defined as the weight of the water displaced by the hull.

That makes the correct description the statement about the weight of the volume of water displaced by the ship. The other ideas describe related concepts—how hard you must pull to keep it afloat, or a hull’s length, or the ship’s total weight—but they do not define displacement itself. (The ship’s total weight is numerically equal to displacement in weight for a floating vessel, but the definition centers on the water displaced.)