1. The problem statement, all variables and given/known data A U shaped smooth wire has a semi circular bending between A and B (A and B are points on the U wire). A bead of mass 'm' moving with uniform speed v through the wire enters the semi circular bend at A and leaves at B. Find the average force exerted by the bead on the part AB of the wire. d is the perpendicular distance between the two arms of the U shape. 3. The attempt at a solution Method 1: As the part betwen A and B is circular Force=mv^2/ (d/2) Method 2: The change in momentum is 2mv time taken to go around AB=pi*(d/2)*(1/v) Force =change in momentum/time I get two different answers from these 2 methods. At least one of them is surely wrong. but which one??? Both seem right to me.