Identify the object’s weight: (W = mg)
Identify the fluid’s density: (rho)
Determine the object’s drag coefficient: (C_d)
Determine the object’s cross-sectional area: (A)
Set net force to zero at terminal velocity: (W = F_{text{drag}} + F_{text{buoyancy}})
Use the drag force equation for high-speed motion: (F_{text{drag}} = tfrac{1}{2}rho C_d A v_t^2)
Include buoyant force if needed: (F_{text{buoyancy}} = rho V g)
Solve for terminal velocity:
(v_t = sqrt{dfrac{2(W – F_{text{buoyancy}})}{rho C_d A}})
If buoyancy is negligible:
(v_t = sqrt{dfrac{2mg}{rho C_d A}})
For low-speed motion in a viscous fluid, use the appropriate linear drag model instead of quadratic drag
Equate weight to drag in the chosen model
Solve the resulting equation for (v_t)