中文摘要：

讨论了半无限长弦的自由振动问题和强迫振动问题,在牛顿定律的基础上建立了弦振动方程并进行了求解;结果表明强迫振动下各质点的振动位移与时间的关系要复杂得多,它不仅与边界点x=0处的振动有关,还与力密度有直接的关系.

英文摘要：

This paper discusses free vibration and forced vibration of half infinite long string, sets up string vibration equation on the basis of Newton Law and tries to solve the equation. The results show that the relation between the time and the vibration displacement of each particle under the forced vibration is much more complex, and that the vibration displacement is not only related to the vibration at the boundary point x = 0 but also is directly related to force density.