Two identical spools are held the same height above the floor. a thread is wrapped many times around spool a. the same thread passes over a pulley, and is attached to a fixed point on spool b, so that spool b will not rotate. an x is marked on the floor directly below each spool. both spools are released from rest at the same instant. (assume that the pulley and thread are massless and that the axle of the pulley is frictionless.)