[单选题]
97.03: A student workiflt0nq p. m.u)7 0+1tye(ti: xhcgn ryng oddkt*dv+ .n;zni ) zo7 w1h2ugj q;s 8qlyq31xn an energy conservation problem has obtained the answer gziq.z8 v* 13nqdu+ 7n1olydkdhjs)qt2w; ;x$50\;J s^2/m^2$. The student has solved for:
