Two blocks, A and B (with mass 35 kg and 120 kg, respectively), are connected by a string, as shown in the figure below. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between block A and the incline is ?k = 0.21. Determine the change in the kinetic energy of block A as it moves from circled C to circled D, a distance of 21 m up the incline (and block B drops downward a distance of 21 m) if the system starts from rest.

Two blocks, A and B (with mass 35 kg and 120 kg, respectively), are connected by a string, as shown in the figure below. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between block A and the incline is ?k = 0.21. Determine the change in the kinetic energy of block A as it moves from circled C to circled D, a distance of 21 m up the incline (and block B drops downward a distance of 21 m) if the system starts from rest.