1. The problem statement, all variables and given/known data A 16.00 lead sphere is hanging from a hook by a thin wire 3.20 long, and is free to swing in a complete circle. Suddenly it is struck horizontally by a 5.50 steel dart that embeds itself in the lead sphere. What must be the minimum initial speed of the dart so that the combination makes a complete circular loop after the collision? 2. Relevant equations 3. The attempt at a solution 1) i've try equating T = mv^2 / r = mg when the sphere reaches the top of the swing. v=5.6 as r = 3.2 and m cancels out. 2) then initial p = final p 5.5 v = (16+5.5) (5.6) i'll get initial v of 21.9m/s for the dart but its wrong. can anyone tell me what's wrong? or should i just the mgh PE at the top approach?