two identical balls, each of mass m, are connected by a unextendible cord of negligible mass and length of 2 another unextendible cord is attached to the first at its midpoint and is pulled vertically with a constant force if the system starts at rest when 0, determine the speed of the two balls using conservation of energy in terms of , , m and 0 as approaches 90 neglect the size of the balls as well as friction between the balls and the surface on whic