Block b, with mass 5. 00 kg, rests on block a, with mass 8. 00 kg, which in turn is on a horizontal tabletop (the figure (figure 1)). There is no friction between block a and the tabletop, but the coefficient of static friction between block a and block b is 0. 750. A light string attached to block a passes over a frictionless, massless pulley, and block c is suspended from the other end of the string.