1. The problem statement, all variables and given/known data A 17.00 kg lead sphere is hanging from a hook by a thin wire 3.00 m long, and is free to swing in a complete circle. Suddenly it is struck horizontally by a 5.00 kg 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 momentum: P1=P2 Force radial=mv^2/R 3. The attempt at a solution Here is the start to my thought process, but it doesn't go anywhere from here. You calculate the circumference of the circle that the combined sphere and dart go. We need to find the V in the Radial force equation which is equal to the sqrt(Frad*radius/mass). We have all of the knowns except for Frad and V (V is the final speed of both objects together for it to go around one loop): radius= 3.0m mass dart = 5kg mass sphere = 17kg I know momentum has a part to play.. You could say P1=P2 5kg(Vd) = 22kg(Vds) (the 22 is the mass of the dart + sphere) and Vds is the final V and now i'm stuck, do I use the radial force equation and substitute 5Vd/22 in for V? I'm still left with an Fradial value which i don't know what to do with.