Two touching bars 1 and 2 are placed on an inclined plane forming an angle \(\alpha\) with the horizontal (Fig. 1.10). The masses of the bars are equal to \(m_{1}\) and \(m_{2},\) and the coefficients of friction between the inclined plane and these bars are equal to \(k_{1}\) and \(k_{2}\) respectively, with \(k_{1}>k_{2} .\) Find: (a) the force of interaction of the bars in the process of motion; (b) the minimum value of the angle \(\alpha\) at which the bars start sliding down.