Sam is skydiving and initially spreads their body out flat during the descent. At point B, Sam brings their arms and legs together and begins to dive head-first in a streamlined shape. Sam's velocity over the duration of the skydive is represented in the graph below.Analyse how Sam is able to reach terminal velocity twice, referencing points A, B and C on the graph.Write 2 paragraphs in your answer.

In the initial phase of the skydive, when Sam spreads their body out flat, they are increasing their surface area which in turn increases air resistance. At point A on the graph, Sam reaches their first terminal velocity. Terminal velocity is the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration. This happens when the force due to gravity is equal to the drag force acting on Sam. Therefore, the velocity remains constant, and Sam is no longer accelerating.

At point B, Sam changes their body position to a more streamlined shape by bringing their arms and legs together. This reduces the surface area and hence the air resistance. With less air resistance, the force due to gravity is now greater than the drag force, causing Sam to accelerate again. As Sam continues to fall, the speed increases and so does the air resistance, until it equals the force of gravity again. This is represented by point C on the graph, where Sam reaches the second terminal velocity. This terminal velocity is higher than the first one because the streamlined shape allows Sam to fall faster before air resistance and gravity balance out.