题目
23.(4.0分)-|||-滑轮使过其质心的水平做1动,质量为m,半化为r,物块质量为m,段绳子不可伸长,流子与轮-|||-无组可滑动, 估求处原原及绳重不计,(D水平,若某解时,化心A速度为说瞬时,乘-|||-功能为 __ _'-|||-1)-|||-一-|||--1 square B-|||-77777777-|||-A dfrac (25)(4)m({v)_(A)}^2 .-|||-B dfrac (3)(4)m({v)_(A)}^2-|||-C dfrac (21)(A)m({v)_(A)}^2
题目解答
答案
:系统动能为整体动能,即为圆轮A和物块的动能之和,圆轮A的动能为$\dfrac {1}{2}3m{{v}_{A}}^{2}=\dfrac {3}{2}m{{v}_{A}}^{2}$,物块的动能为$\dfrac {1}{2}m{{v}_{B}}^{2}=\dfrac {1}{2}m{{v}_{A}}^{2}$,故系统动能为$\dfrac {3}{2}m{{v}_{A}}^{2}+\dfrac {1}{2}m{{v}_{A}}^{2}=\dfrac {2}{2}m{{v}_{A}}^{2}$。
C
C