How this calculator works
Terminal speed occurs when drag equals weight, making acceleration zero. The model assumes a fixed shape, constant Cd and density, a fixed frontal area and negligible buoyancy. Reference shape coefficients are approximate examples; actual values depend on orientation, Reynolds number, Mach number and surface finish. In a dense fluid, buoyancy can materially reduce the net downward force, so this weight-only model may overestimate terminal speed.
Formula
mg=Cd rho A vt^2/2; vt=sqrt(2mg/(rho Cd A)).
Worked example
For m=10 kg, g=10 m/s2, rho=1 kg/m3, A=2 m2 and Cd=1, terminal speed is 10 m/s. A terminal speed of 20 m/s under the same fluid and area conditions requires 40 kg.
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Frequently asked questions
Does the falling object reach this exact speed?
It approaches the limit asymptotically in the ideal model. A finite drop generally ends below it.
Which area should I enter?
Use the projected area facing the flow, matching the reference area used for Cd.
Are shape coefficients universal?
No. Treat the listed values as reference estimates and use measured coefficients when conditions matter.