Water Safety Instructor (WSI) Practice Exam

The concept being described is form drag, which is the resistance experienced by a swimmer's body as they move through water. This type of drag is primarily influenced by the swimmer's shape and positioning in the water. When a swimmer enters the water, their body displaces it, creating turbulence and resistance, which slows them down.

Form drag is one of the main components of drag in swimming, the other being frictional drag. A swimmer with a streamlined body shape will experience less form drag than one who is less streamlined. Therefore, understanding how to minimize form drag by optimizing body position and movements is crucial for improving performance in swimming.

Wave drag, on the other hand, refers to the disturbance created by the movement of the swimmer through the water, leading to the formation of waves. Surface tension is a property of liquids that affects how they behave at the interface with air, but it is not directly about body shape resistance. Hydrodynamic lift is a phenomenon that can assist in buoyancy and forward motion but is not specifically related to the resistance caused by body shape. Thus, the definition of form drag aligns perfectly with the question about the resistance created by a swimmer's body shape.