Advanced physics

4- A flexible but inextensible string connects three blocks of masses M1, M2 and M3 as shows in Figure 4. Assuming the coefficient of friction between block M1 and the horizontal surface to be u and by applying d'Alembert's principle determine the unknown forces and the acceleration of the masses and tensions in the string. Assume that ' -,~ . ' and M3 = 3 Kg and u = 0.25. Figure 4 : Masses M1, M2 and M3