第18题怎么做？详细解答---**Question Number:** 18. (多选) **Question Stem:** 图甲是用力传感器对单摆做小角度摆动过程进行测量的装置图, 图乙是与力传感器连接的计算机屏幕所显示的 F-t 图像, 其中 F 的最大值 F_max = 1.02N, 已知摆球质量 m = 100g, 重力加速度取 9.8 m/s², π² 取 9.8, 不计摆线质量及空气阻力。下列说法正确的是( ) **Options:** A. 单摆周期为 0.8s B. 单摆摆长为 1.0m C. F 的最小值 F_min = 0.96N D. 若仅将摆球质量变为 200g, 单摆周期不变 **Image A Description:** Type: Setup diagram. Main Elements: Shows a physical setup for measuring the force exerted by a simple pendulum during oscillation. A simple pendulum consists of a bob suspended by a string. The string is attached to a force sensor, which is mounted on a support. The force sensor is connected via cables to a computer monitor and other electronic equipment. The diagram is labeled "甲". **Image B Description:** Type: Line chart (F-t graph). Axes: The horizontal axis is labeled "t/s" representing time in seconds. The vertical axis is labeled "F/N" representing force in Newtons. Data Series: A waveform showing the variation of force F as a function of time t. The waveform is oscillatory, resembling a sinusoidal curve. Key Features: The graph shows oscillations between a maximum force F_max and a minimum force F_min. Horizontal dashed lines indicate the levels of F_max and F_min. Peaks of the oscillation occur at approximately t = 0.1 s, 0.9 s, and 1.7 s. Valleys occur between these peaks. The graph is labeled "乙".