Compute centripetal force, radial acceleration, angular velocity, and orbital period for uniform circular motion. Visualize the vector directions (centripetal vs. tangential) on an interactive canvas.
In classical mechanics, centripetal force is the net force that causes an object to follow a curved path, directed toward the center of curvature. For uniform circular motion, the magnitude is constant and given by Fc = m·v² / r or equivalently Fc = m·ω²·r. Despite common misconception, centripetal force is not a separate “type” of force but rather the name for any force (tension, gravity, friction, normal) that pulls an object inward.
$$ Fc = m · ac = m · \frac{v^2}{r} = m · ω²·r $$
where ω = v / r, and centripetal acceleration ac = v² / r.
Newton’s second law states that net force equals mass times acceleration. For circular motion, the acceleration is purely radial (centripetal): ac = v²/r. Therefore Fc = m·v²/r. This relation holds as long as speed is constant. The direction is always perpendicular to the instantaneous velocity vector. The interactive diagram illustrates the centripetal vector (red) pointing to the center and the tangential velocity (blue) orthogonal to it.
A car of mass 1200 kg rounds a curve of radius 50 m at 15 m/s. The centripetal force is provided by tire friction: Fc = (1200 × 15²)/50 = 5400 N. If the coefficient of friction is insufficient, the car will skid outward. Our calculator instantly verifies safe speed limits for curve design.
For a 500 kg satellite at altitude ~200 km (r ≈ 6.7×10⁶ m) with orbital speed ~7800 m/s, the centripetal force equals gravitational pull: Fc ≈ 500 × (7800²)/(6.7e6) ≈ 4540 N. This matches GMm/r², confirming Newton’s law of gravitation.
The tool uses SI units (kg, m, s) and outputs force in newtons (N). All conversions are handled automatically. Avoid zero or negative radius – this yields an error message. For extremely small radii (e.g., < 1e-9 m) the force may become unrealistically large; use caution with microscopic applications.
| Quantity | Symbol | Formula | SI Unit |
|---|---|---|---|
| Centripetal force | Fc | m·v²/r | Newton (N) |
| Centripetal acceleration | ac | v²/r | m/s² |
| Angular velocity | ω | v/r | rad/s |
| Orbital period | T | 2πr/v | second (s) |
The canvas displays a circular trajectory. The red arrow represents the centripetal force direction (toward the center), while the blue arrow shows tangential velocity. In uniform circular motion these two vectors are perpendicular. The length of arrows is scaled proportionally to magnitudes for conceptual clarity.
Christiaan Huygens derived the formula for centripetal force in 1659. Isaac Newton later used it to formulate his law of universal gravitation. Today, centripetal force concepts are essential in fields ranging from astrophysics to mechanical engineering. This calculator’s algorithms are cross-checked with standard physics textbooks (Halliday, Resnick, Krane; University Physics).