(1)绳子自由端移动的距离为s=3h=3×0.5m=1.5m;
(2)∵F=
1
3
(G+G动),
∴动滑轮的重力为G动=3F-G=3×210N-600N=30N.
答:
(1)绳子自由端移动的距离是1.5m;
(2)动滑轮的重力是30N.