Two blocks of masses `m_(1)` and `m_(2)` kept touching each other on an inclined plane of inclination a with the horizontal. Show that (i) theforce of interaction between the blocks is `((mu_(1)-mu_(2))m_(1)m_(2)gcosalpha)/((m_(1)+m_(2)))` and (ii) the minimum value of `alpha` at which the blocks just start sliding is `a = tan^(-1).(mu_(1)m_(1)+mu_(2)m_(2))/(m_(1)+m_(2))` . Where `mu_(1)` and `mu_(2)` are the coefficients of friction between the block `m_(1)` and the inclined plane and between the block `m_(2)` and the inclinedplane respectively.