Centrifuge simulator showing the physics of circular motion. A sample sits at radius r on a rotor spinning at angular velocity ω = 2π·RPM/60. Centripetal acceleration a = ω²r and centripetal force F = mω²r are computed live and expressed in g's, then compared against real centrifuges: washing machines, laboratory benchtop centrifuges, high-speed blood-separation units and ultracentrifuges.
When a sample spins inside a rotor, it does not travel in a straight line — the rotor's wall keeps pulling it toward the axis. That inward pull is the centripetal force, and the resulting inward acceleration is the centripetal acceleration. For a sample at radius r spinning at angular velocity ω (in radians per second, where ω = 2π·RPM/60), the acceleration is a = ω²r and the force needed to hold a mass m on that circular path is F = mω²r. Because acceleration depends on the square of the angular velocity, doubling the rotor's RPM quadruples the g-force — this is why centrifuge speed specifications matter so much more than they might first appear, and why a modest increase in RPM can push a sample from a gentle spin into an enormous acceleration.
This simulation lets you dial in rotor speed (100–15,000 RPM), radius (2–30 cm) and sample mass (1–500 g) and watch angular velocity, acceleration, g-force and force update live, alongside a real-world comparison. The same relationship governs a huge range of technology: clinical centrifuges spin blood samples at a few thousand g to separate plasma from cells, gas centrifuges used in uranium enrichment run at extremely high speeds to separate isotopes by tiny mass differences, human centrifuges train astronauts and fighter pilots to tolerate sustained g-forces, and even an ordinary washing machine's spin cycle uses centripetal force to fling water out of wet laundry through the drum wall.
What does this simulation actually show?
It shows a top-down view of a rotor spinning a sample around a central axis. As you change rotor speed, radius or sample mass, the animation updates the spin rate and the length of the inward-pointing force arrow, while the telemetry panel reports the exact angular velocity, acceleration, g-force and force, plus a real-world comparison for the current g-force.
Why does g-force increase so quickly with RPM?
Centripetal acceleration is a = ω²r, and angular velocity ω is proportional to RPM. Because RPM enters the formula squared, doubling the rotor speed quadruples the acceleration, and going from, say, 1,000 to 10,000 RPM multiplies the g-force by 100. This quadratic scaling is why ultracentrifuges reach enormous g-forces without needing an enormous radius.
What is the difference between centripetal and centrifugal force?
Centripetal force is the real, inward-directed force — provided here by the rotor wall or arm — that keeps the sample moving in a circle instead of flying off in a straight line. Centrifugal force is the outward-feeling effect you notice in the sample's own rotating (non-inertial) reference frame; it is not a separate physical force but the consequence of inertia resisting the true centripetal pull.
The preset buttons jump to representative real machines — a washing machine spin cycle, a laboratory benchtop centrifuge and an ultracentrifuge — each setting rotor speed, radius and sample mass together. The Rotor Speed slider sets RPM (100–15,000), the Radius slider sets how far the sample sits from the rotation axis (2–30 cm), and the Sample Mass slider sets the spinning mass (1–500 g).
Angular velocity is ω = 2π·RPM/60 (converting revolutions per minute to radians per second). Centripetal acceleration is a = ω²r, directed toward the rotation axis. The g-force is that acceleration divided by standard gravity, ag = a/9.81. The force needed to keep the sample on its circular path is Newton's second law applied radially: F = ma = mω²r.
The core relations, a = ω²r and F = mω²r, are exact for uniform circular motion and match real centrifuge physics closely. The simulation treats the sample as a point mass at a fixed radius and ignores secondary effects such as air resistance inside the rotor chamber, the sedimentation behaviour of particles within a fluid sample, motor spin-up dynamics and rotor vibration, all of which matter in real hardware design but do not change the core force relationship shown here.
Acceleration a = ω²r is directly proportional to radius, so doubling the radius at the same RPM doubles the g-force. This is why the outer wall of a rotor experiences more g-force than a point near its centre, and why centrifuge rotor design is a careful trade-off between reaching high RPM and keeping the sample radius small enough to stay within safe stress limits.
A washing machine's spin cycle typically produces tens to a few hundred g at the drum wall. Laboratory benchtop centrifuges used for routine sample prep reach hundreds to a few thousand g. High-speed and refrigerated centrifuges used for blood and cell separation reach into the tens of thousands of g. Ultracentrifuges, used for isotope enrichment and separating viruses or macromolecules, can exceed 100,000 g and, in specialised research units, approach 1,000,000 g.
Any time something moves along a curved path, a centripetal force is bending its motion: a car's tyres grip the road to turn a corner, a satellite's orbit is held by gravity acting as the centripetal force, a fairground ride pins riders against the outer wall, and even a ball on a string being swung overhead needs constant inward tension to keep circling instead of flying straight off.