1 . 如图为某种礼物降落伞的示意图,其中有8根绳子和伞面连接,每根绳子和水平面的法向量的夹角均为
.已知礼物的质量为
,每根绳子的拉力大小相同,则降落伞在匀速下落的过程中每根绳子拉力的大小(重力加速度
取
)最接近( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ac09dc1ca2cdd7aef28c218763d3e4d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f1b1bd0f94ae786c99ded377c0e79a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3960d67499df76159982657fe3a1cbca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/712fae463b81fe21eafd6690ec662043.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2 . 哥哥和弟弟一起拎一重量为
的重物(哥哥的手和弟弟的手放在一起),哥哥用力为
,弟弟用力为
,若
,且
的夹角为120°时,保持平衡状态,则此时
与重物重力
之间的夹角为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5076289823db419f94e9c0c8f4aafd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3fb78c5f885034612c0e030b920143d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/105e4375167e55f565f87b77847c9ad3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d2a97987f71835f519b462f5b8f5957.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5076289823db419f94e9c0c8f4aafd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
A.60° | B.90° | C.120° | D.150° |
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