Question

So...the question is that a coil spring has a force constant of k = 4.0 lb/in. When the spring's axis is inclined at an angle 30 degrees form horizontal, a Weight = 2.0 oz ball is propelled to a height of 6.0 ft. By how much must the spring have been compressed initially?

...What I've done so far is (more or less) figured out acceleration by setting KE(initial) = 0.5mv^2 (I saw a problem once that basically used the point of release as the arbitrary 0 ft point, so as to ignore initial Potential Energy.) Then, I set PE(final) = KE(initial) so 0.5mv^2 = mgh, and v = sqrt(2gh).

Can you assume that acceleration is just g here? Because when I do that, I just get the distance traveled as 6 feet, which is just the height...

Really, I need help.