Science
Terminal speed with quadratic drag
Estimate the speed at which quadratic drag balances an object’s weight.
Calculators / Science / Quadratic fluid drag
Quadratic fluid drag calculator
Estimate drag and the power needed to overcome it at a fixed relative speed.
On this page
Drag force161.7N
Power against drag3,234W
Calculator controls
How to calculate
Estimate drag and the power needed to overcome it at a fixed relative speed.
Drag force =
rho*v^2*Cd*A/2 NPower against drag =
rho*v^3*Cd*A/2 WWorked example
- Fluid density (kg/m³): 1.225
- Relative speed (m/s): 20
- Drag coefficient: 0.3
- Frontal area (m²): 2.2
- Drag force: 161.7 N
- Power against drag: 3,234 W
Assumptions and limits
This is an ideal educational model. Enter quantities in the stated SI units; it does not certify equipment safety or real operating limits. Density and drag coefficient are supplied assumptions; other resistance and propulsion losses are excluded.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Estimate drag and the power needed to overcome it at a fixed relative speed. Power rises with the cube of speed when the entered drag coefficient remains constant.
When this tool is useful
Power rises with the cube of speed when the entered drag coefficient remains constant.
Understanding your inputs
| Input | Example |
|---|---|
Fluid density (kg/m³) rho | 1.225 |
Relative speed (m/s) v | 20 |
Drag coefficient Cd | 0.3 |
Frontal area (m²) A | 2.2 |
Frequently asked questions
Which assumptions matter for this result?
This is an ideal educational model. Enter quantities in the stated SI units; it does not certify equipment safety or real operating limits. Density and drag coefficient are supplied assumptions; other resistance and propulsion losses are excluded.
How can I check the worked example?
Use the displayed example inputs in the stated formula. Keep each quantity in its labelled unit and compare the unrounded result before applying display rounding.