Centripetal force is the net inward force that holds an object on a circular path: F = mv²/r. Drag the sliders below to change the speed and the radius (the mass is fixed), and watch the centripetal force, acceleration, angular velocity and period respond in real time.
An object can travel at perfectly constant speed and still accelerate every instant, because acceleration tracks any change in velocity — and velocity is a direction as much as a number. This simulation makes that idea visible on screen. Drag Speed v and Radius r while the fixed 0.20 kg mass holds steady, and watch the centripetal force F, acceleration a, angular velocity ω, and period T update together as the object rounds its circular path.
Push Speed v higher and F climbs steeply, because F = mv²/r: double v and the inward force quadruples, since v² carries the weight. Radius r pulls the other way — with F proportional to 1/r, doubling r halves the force needed to hold the turn. Every reading obeys the same geometry: a = v²/r sizes the inward pull per kilogram, ω = v/r counts how fast the angle sweeps, and T = 2πr/v times one lap.
The arrow always aims inward, square to the motion, so it bends the velocity without ever speeding the object up. There is no outward force on the object — the "centrifugal" shove you feel is only inertia resisting the turn. Cut the string mid-circle and the object leaves along the tangent, a straight line, not radially outward, exactly as a car slides wide when friction cannot supply mv²/r. Check any turn against the centripetal force calculator, then send another object around the track in our other hands-on simulators.
Centripetal force is the net inward force that keeps an object moving on a circular path, given by F = m·v²/r. It is not a new kind of force — it is supplied by a real agent such as tension, gravity or friction, always pointing toward the centre.
Because acceleration means any change in velocity, and velocity includes direction. In uniform circular motion the speed stays constant while the direction turns continuously, so the object is always accelerating — inward, toward the centre.
It quadruples. Since F = m·v²/r, the force depends on the square of the speed, so doubling v multiplies the required inward force by four. Doubling the radius instead halves the force, because F is inversely proportional to r.
In an ordinary (inertial) frame there is no outward force on the object — the outward push you feel is your own inertia resisting the turn. The only real force is the inward centripetal force. Remove it and the object flies off along the tangent, in a straight line, not outward.