Erratic behavior of sphere and AddForce?

Questions & Answers
1

I'm trying to just push this sphere around a bit, for my pong clone, but it seems to... not work. The sphere Begins to move left (not right), then move up, and down, and all around. Sometimes it somehow breaks its Configurable Joint constraints and moves out into the distance. I really have no idea what is going on. Probably a rookie mistake, a silly error. We'll see.

I have a prefab with one object it in it, the 'ball'. The ball is just a sphere, with a Sphere Collider, Rigid body (which ignores gravity (on purpose!)), a Configurable Joint that locks movement on the Z axis. Also, this script:

var ball : Rigidbody   
function Start() { ball.AddForce(Vector3.right * 50) }

The ball, like I said above, moves to the left (very slowly) at first, then starts acting all... strange.

2

Probably you haven't configured the joint to use worldspace for its constraints, so when the sphere rotates the local coordinate system changes and therefore the constraints change as well.