When we watch a flying kite with a long tail hanging beneath, the tail sometimes oscillates and sometimes maintains a static shape. Generally, the tail portion deviates more when moving toward the free (bottom) end. The shape of the tail is described by a zeroth-order Bessel function where the coordinate origin locates at the tail’s bottom. In this paper, we derive simple equations to qualitatively explain the tail profile under a horizontal wind. We discuss three possible states: static bending, oscillations with small displacements around the vertical axis, and oscillations with small displacements around the static bending state. We find that the deviations of the small oscillations satisfy the zeroth-order Bessel function of the first kind. Since this work is aimed as reading material for teachers or undergraduate students, some approximations were performed for the sake of simplicity so that the solution can be obtained from standard mathematical procedures taught at the undergraduate level.

当我们观看下面垂着长尾巴的风筝时，尾巴有时会摆动，有时会保持静止的形状。通常，尾部向自由（底部）端移动时偏离更多。尾部的形状由零阶贝塞尔函数描述，其中坐标原点位于尾部底部。在本文中，我们推导出简单的方程来定性地解释水平风下的尾部轮廓。我们讨论了三种可能的状态：静态弯曲、绕垂直轴小位移的振荡和绕静态弯曲状态小位移的振荡。我们发现小振荡的偏差满足第一类零阶贝塞尔函数。由于本作品旨在作为教师或本科生的阅读材料，