Terminal velocity is the constant speed a falling object reaches once air resistance balances its weight. Drag the sliders below to change the mass, cross-sectional area and drag coefficient, and watch the drag force climb and the speed level off in real time.
Interactive Lab · Mechanics
Terminal Velocity — when drag balances weight
Drop the object and watch drag grow until it cancels weight. Time is compressed to a few seconds; the curve is the exact v = vt·tanh(g·t / vt).
What Is the Terminal Velocity Simulator?
The terminal velocity simulator is a free interactive physics lab that runs in your browser — nothing to install and no sign-up. Change the mass, cross-sectional area and drag coefficient and watch drag rise until it balances weight.
| Control | Range | Step |
|---|---|---|
| Mass | 1 – 150 kg | 1 |
| Cross-sectional area | 0.05 – 2 m² | 0.05 |
| Drag coefficient Cd | 0.1 – 1.5 | 0.05 |
Why the falling object in this sim stops speeding up
Nothing falling through air can speed up without limit, and this simulation shows exactly where the acceleration runs out. Released from rest, the mass picks up speed, and as it does the drag force climbs with the square of that speed: F = 1/2 · rho · C · A · v². Watch the Drag force readout climb until it matches the object's weight. The instant drag equals weight, the net force hits zero, acceleration stops, and Current speed settles onto the value shown as Terminal velocity. The object is still falling and still has weight here — gravity and drag are balanced, not gone.
Now push the sliders. Raise Mass and terminal velocity rises; widen Cross-sectional area or nudge up Drag coefficient C and it drops, because those sit under the root in v_t = sqrt(2 · m · g / (rho · C · A)). Air density and gravity stay fixed on the panel, so every change you see traces back to those three inputs. The square root tempers each one: quadruple the mass and terminal velocity only doubles. The area and drag-coefficient terms soften the same way, so a skydiver tucking from a spread belly-down posture into a head-first dive cuts both the frontal area and the drag coefficient their body presents, and speeds up sharply — a real, sizeable jump, though the square root keeps it gentler than the drop in drag driving it.
Match your slider settings against the terminal velocity calculator to confirm the number, then wander into more falling, spinning, and oscillating systems waiting in our library of interactive physics sims.
Frequently asked questions
What is terminal velocity?
Terminal velocity is the steady speed a falling object reaches when the drag force pushing up exactly balances its weight. The net force is then zero, so it stops accelerating and falls at a constant speed.
What does terminal velocity depend on?
On the object's mass, its cross-sectional area and its drag coefficient (plus the air density): v_t = sqrt(2·m·g/(ρ·C·A)). A heavier object reaches a higher terminal speed; a larger area or drag coefficient lowers it.
Does a heavier object have a higher terminal velocity?
Yes. Because v_t is proportional to the square root of the mass, more mass means a higher terminal speed for the same shape. The square root softens it, though — quadrupling the mass only doubles the terminal velocity.
Why doesn't a falling object keep speeding up forever?
Because drag grows with the square of the speed. As the object accelerates, drag rises until it equals the weight; from that moment the forces balance, the acceleration drops to zero, and the speed levels off at terminal velocity. The object is not weightless — gravity and drag simply cancel.
References & formula source
- Halliday, Resnick & Walker — Fundamentals of Physics, Chapter 6 (Force and Motion II), drag and terminal speed.
- Young & Freedman — University Physics with Modern Physics, §5.3 (Frictional Forces; Fluid Resistance).
- R. Nave — HyperPhysics, Georgia State University, "Terminal Velocity" section.
- Further reading: Terminal velocity — Wikipedia