force analysis
Force analysis of moving pulley: upward rope tension = 400N * 3；; Downward = dead weight (X)+ weight (900N), moving at a uniform speed, the force balance equation of the column is obtained: 400N*3=900N+X, X = 300N n.
♂? Maximum lifting weight
The maximum force that the worker can provide to the rope is equal to the worker's own weight (not given in the title). Let the weight of the soil that can be lifted at most be y, then the force on the moving pulley will be balanced. Equation: Worker's own weight (? ) * 3 = y+300 n (already found in 1), just find y.
Application scenario
Moving pulleys are widely used in construction, logistics and other fields. It can change the direction and length of the rope and realize the function of lifting and moving objects.