🌀 Circular Motion & Centripetal Force

Circular Motion Simulator: Centripetal Force & the Cut-String Test

This circular motion simulator shows why an object on a string travels in a circle: a centripetal force F = mv²/r constantly pulls it toward the centre, bending its otherwise straight-line motion. Live arrows show that inward force (red) and the tangential velocity (blue), and a card reports the force, angular speed, and period as you change radius, speed, and mass — revealing that the required force grows with the square of speed and inversely with radius. The headline feature is the cut-string test: release the string and the object flies off along the tangent, the direction it was already moving, obeying Newton's first law. The simulation draws both the correct tangential path and the common 'radially outward' misconception so the difference is unmistakable — there is no outward force, and the 'centrifugal' feeling is just inertia. Predict the escape direction before you cut.

What you can do in this simulation

• Whirl an object and watch the centripetal force arrow point to the centre while velocity stays tangent
• See F = mv²/r, angular speed, and period update as you change radius, speed, and mass
• Cut-string test: the object flies off along the tangent, with the 'radially outward' myth drawn for contrast
• Predict mode: call tangent vs outward vs inward before releasing, with a score
• Feel how tight, fast turns demand far more force — the physics behind banked roads and orbits

Concepts covered

circular motion · centripetal force · tangential velocity · newton's first law · centrifugal misconception · angular speed · F = mv^2/r

Related simulations

• Acoustics & Sound Waves — Interactive Simulator
• Angular Momentum Simulator: The Spinning Skater Effect
• Black Hole Simulator — Gravity & Spacetime
• Brachistochrone Curve Simulator - Fastest Ramp
• Buoyancy Simulator: Archimedes' Principle, Float or Sink?
• Center of Mass Simulator: Balance Point Explained

Browse all Physics simulations →

Free to use in your browser — no signup required. Found a bug or have an idea to make it better? Tell us.