Algodoo

I'd like to see some brilliant mechanical engineer design a zero-length spring in the real world.

Interesting scene.

"There are several ways to make a zero length spring." See PHYSICS OF THE GRAVITY SENSOR.

Also see Zero Length Spring Linkage.

Thanks, s_noonan! That article about the physics of the Gravity Sensor is very interesting. I love that kind of stuff!

Well, since both springs as gravity use potential energy(energy saved in your position), it makes sense how these balls fly around the spring: A distance of 0 is identical to some gravitational centrum, with the only difference that, the further away, the stronger the force, instead of vice-versa. Since both gravity as this spring pull the object to 1 single point, while converting potential in kinetic energy, they are basically pure inversions of each other. The reason why the balls fly under the spring is just the scene gravity, pulling the potential centrum downwards.

OK.