(20 1 1? Nanning) As shown in the figure, use the pulley block to lift an object weighing 5N by 0.2m at a uniform speed, so that the tension at the rope end is _ _ _ _ n, and the free end of the rope moves. In the figure, the tension at the rope end, that is, the pointer of the spring dynamometer is 2N, so the pulley block hangs the object with three ropes, and the distance at the free end of the rope is s = 3h = 3× 0.2m = 0.6m.

The mechanical efficiency of pulley block η=W is wtotal = ghfs = 5n× 0.2m2n× 0.6m = 83.3%.

So the answer is: 2,0.6,83.3%.