What keeps things moving in circles?

Circular motion: F = m v² ÷ r. Anything going round in a circle is changing direction all the time, so something must keep pulling or pushing it towards the centre: a string, friction, a wall or gravity. The faster it goes and the tighter the circle, the harder that pull must be.

Read how it works: What keeps things moving in circles? · The history of circular motion · More boxes on Glassbox

Chapters in this interactive model

1. Going round in a circle needs a pull to the centre: Double the speed and you need four times the pull.
2. Spinning machines: washers, mixers, fans and centrifuges: The faster and wider the spin, the harder the wall must push.
3. Cornering: friction, banked roads and leaning: Something must push you towards the centre of the bend.
4. Loops, giant wheels, the wall of death and space: Feel heavier, lighter, stuck to a wall, or weightless.
5. Centrifugal force, Coriolis and the sink myth: Nothing flings you outwards. You just keep going straight.