Case 1
- Mass (kg)
- 2kg
- Speed (m/s)
- 5m/s
- Radius (m)
- 10m
5.000N
Open with these valuesCentripetal Force Calculator
5.000N
Result: 5.000 NMultiply the mass by the speed squared and divide by the radius: 2 kg at 5 m/s on a 10 m circle needs 5 N. It is the same as the centripetal acceleration times the mass. Doubling the speed quadruples the force; doubling the radius halves it.
Worked examples
Case 2
- Mass (kg)
- 1000kg
- Speed (m/s)
- 20m/s
- Radius (m)
- 50m
8,000.000N
Open with these valuesCase 3
- Mass (kg)
- 70kg
- Speed (m/s)
- 3m/s
- Radius (m)
- 1.5m
420.000N
Open with these valuesHow it's calculated
F = m × v² ÷ r
- StepEnter the mass of the object in kilograms.
- StepEnter its speed along the circle in m/s — divide km/h by 3.6.
- ResultEnter the radius in metres and read the inward force in newtons.
Reference table
| m (kg), v (m/s), r (m) | What it describes | Force (N) |
|---|---|---|
| 2, 5, 10 | A 2 kg ball on a wide 10 m circle | 5 |
| 0.5, 4, 1 | Small mass whirled close in | 8 |
| 1, 10, 2 | 1 kg on a 2 m string, swung fast | 50 |
| 70, 3, 1.5 | Person on a fairground ride | 420 |
| 1000, 20, 50 | Car cornering at 72 km/h | 8000 |
Questions
How do I calculate centripetal force?
Multiply the mass by the speed squared and divide by the radius: F = m × v² ÷ r. Use kilograms, metres per second and metres to get the force in newtons. A 2 kg object at 5 m/s on a 10 m circle needs 2 × 5² ÷ 10 = 5 N.
What is centripetal force?
It is the net inward force that keeps an object moving along a circular path, always pointing toward the centre. It is not a new kind of force — it is whatever real force happens to supply that inward pull, be it tension, friction, gravity or a normal force. Without it the object would fly off in a straight line.
Why does doubling the speed quadruple the force?
Because the speed is squared in F = m × v² ÷ r. Doubling it multiplies the force by four and tripling it by nine. That is why a car needs far more grip to corner fast, and why a quicker spin strains a string much harder.
What is the difference between centripetal and centrifugal force?
Centripetal force is the real inward force that bends an object's path into a circle. Centrifugal force is the apparent outward push you feel in a rotating frame of reference. It is a fictitious force that arises only because you are accelerating with the object, not a force acting on the object itself.
Which units should I use?
Kilograms for the mass, metres per second for the speed and metres for the radius, which gives the force in newtons. If your speed is in km/h, divide by 3.6 first. One newton is one kg·m/s², the force that accelerates 1 kg by 1 m/s².
Sources and last check
Information, not professional advice.