Junior high school physics mechanics part -- pulley problem It is composed of four identical pulleys and two identical ropes as shown in the figure (it will not be uploaded. Roughly, two pulley blocks a and B are composed of a movable pulley and a fixed pulley. There are two sections of rope on the movable pulley of a and three sections of rope on the fixed pulley of B. two weights are hung on the two pulley blocks). The pulley blocks a and B lift the two identical hooks by 10cm respectively, If the friction between the rope and the pulley is not taken into account, the device is more labor-saving (select "a" or "B"). The mechanical efficiency of device a is the mechanical efficiency of device B (select "higher", "lower" or "equal") Second, my calculation is as follows According to the formula of mechanical efficiency: η= W is useful General manager w =G divided by FN The denominators of a and B are the same, and the n of a is small, so the efficiency of a should be greater than that of B But why is the answer equal What's wrong with me? Which master will guide me

Junior high school physics mechanics part -- pulley problem It is composed of four identical pulleys and two identical ropes as shown in the figure (it will not be uploaded. Roughly, two pulley blocks a and B are composed of a movable pulley and a fixed pulley. There are two sections of rope on the movable pulley of a and three sections of rope on the fixed pulley of B. two weights are hung on the two pulley blocks). The pulley blocks a and B lift the two identical hooks by 10cm respectively, If the friction between the rope and the pulley is not taken into account, the device is more labor-saving (select "a" or "B"). The mechanical efficiency of device a is the mechanical efficiency of device B (select "higher", "lower" or "equal") Second, my calculation is as follows According to the formula of mechanical efficiency: η= W is useful General manager w =G divided by FN The denominators of a and B are the same, and the n of a is small, so the efficiency of a should be greater than that of B But why is the answer equal What's wrong with me? Which master will guide me

Because the tension f is different
The mechanical efficiency is G + G without friction