1:F向心力=mv^2/r=2*16/1=32N;
F向心力=G+F拉力=mg+F拉力;
F拉力=12N;方向竖直向下.
2:F向心力=mv^2/r=2*16/1=18N;
F向心力=F拉力-G=F拉力-mg;
F拉力=38N; 方向竖直向上.