第6题---Here is the extracted content from the image, presented in a structured plain text format: --- **General Information/Context:** * **Source Book (left page):** 高中必刷题数学必修第一册 158 (High School Must-Do Problems Mathematics Compulsory Book 1, Page 158) * **Source Book (right page):** 2026版《高中必刷题》物理 RJ 必修1 (2026 Edition "High School Must-Do Problems" Physics RJ Compulsory Book 1) --- **Question 3:** **Question Stem:** [浙江多校 2025 高一联考] 2025 年 3 月 21 日, 历时约 7 小时, 神舟十九号载人飞船的航天员圆满完成第三次出舱活动, 完成了空间站空间碎片防护装置安装、舱外设备巡检等任务, 如图所示. 下列说法正确的是 ( ) **Options:** A. 执行载人飞船与核心舱交会对接时, 可将载人飞船看作质点 B. 研究航天员出舱太空行走时的姿态时, 可将航天员看作质点 C. 操作机械臂旋转的过程中, 可将机械臂看作质点 D. 研究载人飞船绕地球运行一周的时间, 可将载人飞船看作质点 **Other Relevant Text:** 注:2024 表示 2023~2024学年,2025 表示 2024~2025学年. **Chart/Diagram Description:** * **Type:** Photographic image. * **Main Elements:** The image shows what appears to be a spacecraft (Shenzhou-19 manned spacecraft) or a space station module, with an astronaut potentially performing extravehicular activity (EVA) or working on the exterior. The image is illustrative for the context of the problem. --- **Question 6:** **Question Stem:** [福建泉州四校 2025 高一联考] (多选) 如图所示, 一辆车沿着笔直的公路做匀速直线运动. 某时起, 位于车厢中间位置的甲、乙两人分别以相同大小的速度朝着车厢的前、后壁移动, 经过一段时间, 甲到达车厢前壁的同时, 乙刚好到达车厢后壁. 则在这段时间内 **Options:** A. 甲乙两人相对地面移动的速度大小相等 B. 甲乙两人相对车厢移动的速度大小相等 C. 站在地面不动的人观察到甲一定向东移动 D. 站在地面不动的人观察到乙一定向西移动 **Chart/Diagram Description:** * **Type:** Simple schematic diagram illustrating a moving vehicle with two people inside. * **Main Elements:** * **Vehicle:** Represented by a horizontal rectangle (labeled "车厢" - carriage) with two circles underneath, indicating wheels. * **People:** Two small figures inside the carriage, initially positioned in the middle, labeled "乙" (Yi) on the left and "甲" (Jia) on the right. * **Ground:** Indicated by a wavy line below the vehicle. * **Directions:** Handwritten labels "西" (West) on the left side of the diagram and "东" (East) on the right side. An arrow underneath the vehicle points from West to East, indicating the direction of the vehicle's motion. ---

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In physics, a reference frame is a coordinate system from which we observe and measure motion. Understanding reference frames is crucial because the same motion can appear completely different when viewed from different frames. For example, a person sitting in a moving car appears stationary relative to the car, but is moving relative to the ground. Choosing the proper reference frame can greatly simplify motion analysis. Let's analyze the problem setup carefully. We have a car moving eastward at constant speed. Inside the car, two people named 甲 and 乙 start at the center position. They move with equal speed magnitudes but in opposite directions relative to the car - 甲 moves toward the front of the car while 乙 moves toward the back. Since they have equal relative speeds and travel equal distances, they arrive at the car walls simultaneously. We need to establish two reference frames: the ground frame fixed to Earth, and the car frame moving with the car. The coordinate system shows positive x direction as eastward. Now let's analyze the motion from the car's reference frame. In this frame, the car appears stationary, and we only observe the relative motion of the two people. Person 甲 moves toward the front wall with velocity positive v_rel, while person 乙 moves toward the back wall with velocity negative v_rel. The key insight is that both people have equal speed magnitudes relative to the car, just in opposite directions. Since they start from the center and travel equal distances to reach opposite walls, and they have equal speeds, they must take the same time to complete their journeys. This explains why they arrive at the walls simultaneously. 今天我们来分析第6题，这是一道关于运动相对性的物理题。题目描述了一辆在笔直公路上匀速行驶的汽车，车厢内有甲、乙两人分别以相同速度向车厢前后移动的情况。我们需要分析在不同参考系下观察到的运动情况。 首先我们设定具体的运动情境。汽车沿笔直公路匀速向东行驶，甲、乙两人最初位于车厢中央位置。根据题意，两人相对于车厢的运动速度大小相等，但方向相反：甲向车厢前壁移动，也就是向东；乙向车厢后壁移动，也就是向西。 现在我们从车厢参考系来分析这个问题。在车厢参考系中，甲、乙两人相对于车厢的速度大小确实相等，这是题目明确给出的条件。甲向车厢前方移动，我们可以记为正的相对速度；乙向车厢后方移动，记为负的相对速度。因此选项B'甲乙两人相对车厢移动的速度大小相等'是正确的。 现在我们转换到地面参考系，使用速度叠加原理进行分析。每个人相对地面的速度等于汽车速度加上他们相对汽车的速度。对于甲，由于他相对汽车向前运动，所以地面速度是车速加上相对速度，使他向东运动得更快。对于乙，由于他相对汽车向后运动，地面速度是车速减去相对速度。这意味着乙相对地面的运动速度比汽车慢，甚至可能向西运动。关键是两人相对地面的速度大小通常不相等，这与车厢参考系中的情况不同。 现在我们逐一分析每个选项。选项A说甲乙两人相对地面移动的速度大小相等，这在一般情况下是不正确的，因为甲的地面速度是车速加相对速度，而乙的地面速度是车速减相对速度，两者通常不相等。选项B说甲乙两人相对车厢移动的速度大小相等，这是正确的，因为题目明确给出了这个条件。选项C和D涉及方向判断，都不一定正确，因为最终的运动方向取决于车速与相对速度的大小关系。当车速大于相对速度时，乙仍然向东运动；只有当相对速度大于车速时，乙才向西运动。因此，正确答案是选项B。