I believe the formula you want to use would be:
H = Vf*t - 1/2*a*t^2
H = the height that the balls fell...AKA 92.4 cm.
Vf = the final velocity of the balls, right before impact (what you're solving for)
t = the time it took to fall
a = the acceleration due to gravity, which is...
Oh, and your acceleration of (9.81 - 2) is kind of odd. I'm not sure where you're getting the -2 from, seeing as how acceleration of gravity will always be 9.81 (generally speaking).
Torque (moments) is all relative to where you set your datum. So for instance, if you set your datum to be the end from which the dimensions are measured from, you'll get a torque of:
F*d(distance to force from datum)
F = the force due to gravity...i.e. 2kg*9.81m/s^2 = 19.62 N
d = 15 cm...
Oh, and it seems to me that it would be T*6*sin30, and not cos30.
When calculating moments, you use the component of force perpendicular to the object it is acting upon.
Since it's a static problem (no motion), you're just summing the moments, which equals zero (because it's static).
Anyway, since it seems you were using point A as your datum, the value for y would be 3 (because the force of the bridge acts at its center of gravity...the middle of...
If you pick up a rock and throw it in the air, it will come back down to earth. It does this because there is an unbalanced force (gravity, frictional forces (from air resistance), etc.) acting on it.
I did indeed come with them(well, got the link from where they came from), but I didn't really post anything wrong (to my knowledge), other than the body temperature...but using Newton's cooling equation, you need the atmospheric temperature.
Anyhow, I love my physics and want to keep posting...
I might be of some assistance with the questions, but have no idea who this Larry fellow you're referring to is.
Oh, and please don't delete my account again. I'm only trying to help :)