(1)细线拉力T=mv^2/R-mg=1kgX(6m/s)^2/0.3m-1kgX9.8m/s^2=110N
(2)细线拉力T=mv^2/R+mg=1kgX(9m/s^2)/0.3m+1kgX9.8m/s^2=280N