Ball physics help

Can't you just restrict the rotation of the blue cylinder and green box in the rigidbody constraints? Unless there is something else you aren't saying that you need that should keep the box in the center and the ball can go wherever it wants.

You might have to play around with the child/parenting of the objects, to let the box take the balls position, but the box shouldn't rotate with it.

The box needs to be able to rotate but it's weight will keep it almost not moving.

Remember, this is a simulation, I'm trying to get it to be as real as possible.

Let me try to break it down to parts.

Right now I have a ball.

The ball has a rigidbody with sphere collider.

I'm trying to use this code to move it:

 void FixedUpdate() {
         if(Input.GetButton("BallForward")){
             power = 10
         rigidbody.AddRelativeForce(transform.forward * power);
         }    
         if(Input.GetButton("BallBackward")){
             power = -10;
         rigidbody.AddRelativeForce(transform.forward * power);
         }    
     }

But for some reason, the ball starts moving forward and then its going back (while I still have the key pressed) like something is trying to hold it in place.

Ok, nvm I solved the problem.

It was very weird.

If the script was on the object, it didn't work.

The second I put the script on a different object, it worked :S

Now for another part:

I managed to attached the center box(green) to the bar in the middle(blue) but I'm not sure what's the best way to create the weight.

Can you put an empty/non-rendered game object on the bottom of the box and add mass? Connect it the same way you did with the box to bar.