Two identical balls, each of mass m, are connected by a string of negligible mass and leng...

Two identical balls, each of mass m, are connected by a string of negligible mass and length 2l. A short string is attached to the first at its middle and is pulled vertically with a constant force P (exerted by the hand). If the system starts at rest when θ = θ0, determine the speed of the two balls as θ approaches 90°. Neglect the size of the balls as well as friction between the balls and the surface on which they slide.

Figure P4.61