In the system shown in the figure, m₁=1 kg; m₂=1.2kg; m₀=0.6kg. The coefficient of friction between the body m₁ and the horizontal surface is 0.1. Consider the block as a homogeneous disk, there is no thread sliding along the block, and neglect the friction in the axis of the block. At the moment t=0, the body m₂ starts to descend. Find the work of the friction force acting on the body m₁ during the first 3 s of motion.