[Encyclios]

Forces associated with fluids (include liquids and gases)

• Buoyancy (B, F_b) – The force exerted on an object immersed in a fluid. Buoyancy is usually directed up (although there are exceptions to this rule).
• Drag (R, D, F_d) – The force that resists the motion of an object through a fluid. Drag is directed opposite the direction of motion of the object relative to the fluid.
• Lift (L, F_ℓ) – The force that a moving fluid exerts as it flows around an object; typically a wing or wing-like structure, but also golf balls and baseballs. Lift is generally directed perpendicular to the direction of fluid flow (although there are exceptions to this rule).
• Thrust (T, F_t) – The force that a fluid exerts when expelled by a propeller, turbine, rocket, squid, clam, etc. Thrust is directed opposite the direction the fluid is expelled.