Circular Motion Simulation
An object going round at a steady speed is still accelerating, which is one of the least intuitive facts in mechanics. This simulation draws the velocity and acceleration vectors as the object circles, showing why the acceleration points inwards.
How to use this simulation
- Change the speed, radius and mass
- Show the velocity and acceleration vectors
- Cut the string mid-motion to see what happens
What to look for
- Acceleration points to the centre while velocity stays tangential
- Halving the radius doubles the required force at the same speed
- Releasing the object sends it off along the tangent, not radially outwards
The physics behind it
In uniform circular motion the speed is constant but the velocity direction changes continuously, so there is an acceleration a = v²/r directed towards the centre. The force producing it, F = mv²/r, is called centripetal and is always supplied by something real — tension, friction, or gravity. There is no outward force acting on the object.