An object moving in a circle constantly changes direction, which requires a force toward the centre, from tension, friction or gravity.
How to use the Centripetal Force Calculator
- Mass
- Speed
- Radius
- Want to work backwards? Type a value into Centripetal force and Speed is calculated for you.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Square the speed, multiply by mass and divide by the radius.
Inputs explained
| Field | What to enter |
|---|---|
| Mass | Units: kg, lb, g, oz, st |
| Speed | Units: m/s, km/h, mph, ft/s, knots |
| Radius | Units: m, cm, mm, km, in, ft … |
What each result means
- Centripetal force = [Mass] × [Speed]^2 ÷ [Radius]
- Centripetal acceleration = [Speed]^2 ÷ [Radius]
Example values
How the main result changes when Speed changes and everything else stays at the example values above:
| Speed (m/s) | Centripetal force (N) |
|---|---|
| 10 | 2,000 |
| 15 | 4,500 |
| 20 | 8,000 |
| 25 | 12,500 |
| 30 | 18,000 |
| 40 | 32,000 |
Formula
F = m v² ÷ ra = v² ÷ rWorked example
Inputs — Mass: 1,000 kg; Speed: 20 m/s; Radius: 50 m.
Results — Centripetal force = 8,000 N; Centripetal acceleration = 8 m/s².
Frequently asked questions
Is centrifugal force real?
It is a fictitious force felt in the rotating frame; from outside, only the centripetal force acts.
What supplies centripetal force for a car on a bend?
Friction between the tyres and the road.
What formula does the Centripetal Force Calculator use?
F = m v² ÷ r.
Can I work backwards from the result?
Yes. Type the result you want into Centripetal force and the calculator finds the matching speed.