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试题分析:达到稳定状态时,a沿斜面方向受到自身重力的分力
![](https://img.yulucn.com/upload/5/5b/55b4bb37562cee66e59ba40ce96ebfff_thumb.jpg)
沿斜面向下,弹簧压缩状态的弹力
![](https://img.yulucn.com/upload/a/65/a651c2eebf1323838235256f6c39dd49_thumb.jpg)
沿斜面向下,a要保持平衡,必须受到沿斜面向上的摩擦力,摩擦力一定不等于0,选项A对。分析
![](https://img.yulucn.com/upload/3/54/35474f7d4490639676461f50bb61cfce_thumb.jpg)
沿斜面方向有其重力沿斜面向下的分力
![](https://img.yulucn.com/upload/e/4c/e4cad5643f14d2bf048c557b567574c0_thumb.jpg)
,弹簧向上的弹力
![](https://img.yulucn.com/upload/a/65/a651c2eebf1323838235256f6c39dd49_thumb.jpg)
和绳子向上的拉力
![](https://img.yulucn.com/upload/6/50/65069e79556dc38b9491b902127af716_thumb.jpg)
,若
![](https://img.yulucn.com/upload/5/6f/56ff5bad56f21a1659d804a5a6cac9e5_thumb.jpg)
,则b受摩擦力为0,选项B错。在细绳剪断瞬间,弹簧弹力不变,对
![](https://img.yulucn.com/upload/a/a4/aa40846d0617136543a1034c61d2bbae_thumb.jpg)
分析,弹力不变, 受力情况不变,仍处与平衡状态,合力一定为0选项D对。对
![](https://img.yulucn.com/upload/3/54/35474f7d4490639676461f50bb61cfce_thumb.jpg)
而言,绳子拉力有变化,
![](https://img.yulucn.com/upload/3/54/35474f7d4490639676461f50bb61cfce_thumb.jpg)
是否平衡无法判断,选项C错。
1年前
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