The drag force is the same as the
resistive force. There are a number of different forms of
drag that decelerate a swimmer:
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The exact net drag of a swimmer is difficult to calculate because of a couple main reasons. The flow of a swimmer is not constant throughout and the acceleration/deceleration makes a significant difference in the drag force. The constant stress on the water complicates the flow by allowing wave drag and ventilation. Also, the area of the water varies with the change in pressure due to the change in density caused by air bubbles. Overall, we can estimate the force of drag of a swimmer by using the drag equation for fluid dynamics.
The equation for the force of drag, F(D) is given by the following equation:
F(D)= (1/2)pv^2CA
Where p equals mass density of the water
v is the velocity of the swimmer
A is the swimmer’s surface area
C is the drag coefficient, which is a constant depending on the shape of an object
The best estimate for the drag on a swimmer is computed by using the drag created from the hand.