# Physical units in fluid dynamics

In fluid dynamics, the drag equation is a formula used to calculate the force of drag experienced by an object due to movement through a fully enclosing fluid

$F_D=\frac{1}{2} C_D ρv^2 A$ where

• $F_D$ is the drag force, which is by definition the force component in the direction of the flow velocity,
• $ρ$ is the density of the fluid,
• $v$ is the velocity of the object relative to the fluid,
• $A$ is the reference area, and
• $C_D$ is the drag coefficient.

What units can the quantity $(C_D )^2$ have?

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