A bead of mass 2m can slide on a smooth horizontal wire. A particle of mass m is attached to it by a string of length L and released from the wire with string taut. When the string makes angle θ with the wire, the bead has moved:

Question

G1 Physics · Accepted Answer

With zero external horizontal force, the centre of mass has constant velocity and ΣmᵢΔxᵢ = 0 in the centre-of-mass relation. Applying this to the given motion gives C: (L/3)(1-cosθ).