A truck of mass 1200 kg moves over an inclined plane raising 1 in 20, with a speed of 18 kmph. The power of the engine is
(g = 10 m/s\(^{-2}\)):
Find the least horizontal force \( P \) to start motion of any part of the system of three blocks resting upon one another as shown in the figure. The weights of blocks are \( A = 300 \, {N}, B = 100 \, {N}, C = 200 \, {N} \). The coefficient of friction between \( A \) and \( C \) is 0.3, between \( B \) and \( C \) is 0.2 and between \( C \) and the ground is 0.1.