Drag (physics)
For a solid object moving through a fluid, drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid flow. It therefore acts to oppose the motion of the object, and in a powered vehicle it is overcome by thrust. Types of drag include form drag, pressure drag, lift-induced drag, and wave drag. The overall drag of an object is characterized by a dimensionless number called the drag coefficient, and is calculated using the drag equation.
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