Uniform Circular Motion
Swing a mass on a string in a horizontal circle at a chosen radius and constant speed — see the centripetal acceleration, force, and period, and watch the force grow with the square of speed.
Preview — sign up free to change the numbers yourself
What you can adjust
- Radius
- 0.5 – 10 m
- Speed
- 0.5 – 20 m/s
- Mass
- 0.1 – 10 kg
The string length — the mass's fixed distance from the pivot.
Constant tangential speed around the circle — try dragging it up and watch the required inward force grow with the SQUARE of speed.
Heavier mass needs proportionally more centripetal force to hold the same circle.
About this simulation
What it shows
A mass on a string swings in a flat circle at constant speed, with arrows for its velocity and the inward force that holds it on the circle.
The key idea
Going round a circle needs an inward force of mv²/r, which points to the centre. The speed stays the same but the direction keeps changing, so there is always an acceleration v²/r.
Try this
Double Speed from 4 to 8 m/s: the inward force you need becomes four times larger, because it grows with the square of the speed.