题现有一个弹簧测力计(可随便找地方悬挂),一把匀质的、长为l的、有刻度且刻度零点位于端点的直尺,一个木块及质量不计的细线．试用这些器件设计一实验装置(要求画出示意图),通过一次测量(弹簧测力计只准读一次),求出木块的质量和尺的质量．(已知重力加速度为g) There is a spring dynamometer (you can easily find the place to hang), a straight, a ruler, a ruler with a scale whose zero point is at the end, a wooden block, and a thin line of unmatched quality. Try these devices to design an experimental device (required to draw a schematic diagram), through a measurement (spring dynamometer only read once), find the mass of the wood and the quality of the ruler. (The known gravitational acceleration is g)