论文部分内容阅读
原题再现(2007年全国卷Ⅰ第24题)如下图所示,质量为m的由绝缘材料制成的球与质量为M=19m的金属球并排悬挂.现将绝缘球拉至与竖直方向成θ=60°角的位置自由释放.下摆后在最低点处与金属球发生弹性碰撞.在平衡位置附近存在垂直于纸面的磁场.已知由于磁场的阻尼作用,金属球将于再次碰撞前停在最低点处.求经过几次碰撞后绝缘球偏离竖直方向的最大角度将小于45°.
Reproduce the original title (2007 National Vol. I Item 24) As shown in the following figure, a ball made of insulating material with a mass m and a metal ball with a mass of M=19m are hung side by side. Now the insulating ball is pulled to vertical The orientation is free at the angle of θ=60°. After the hem, elastic collision with the metal ball occurs at the lowest point. There is a magnetic field perpendicular to the paper surface near the equilibrium position. It is known that the metal ball will be again due to the damping effect of the magnetic field. Stop at the lowest point before the collision. After a few collisions, the maximum angle from which the insulation ball deviates from the vertical will be less than 45°.