题目

（1）研究“共点力的合成”时得到的实验结果为如图所示（F′与A、O共线，A端为固定橡皮条的图钉，O为橡皮条与细线的结点），需要进行比较的是                                                                      和                          ；（填“F1”、“F2”、“F”或“F′”）通过本实验可以验证                                                                                   ． （2）在上述实验中所说的合力与两个分力具有相同的效果，是指下列说法中的           ．                               A、弹簧秤的弹簧被拉长                                                                B、固定橡皮条的图钉受拉力产生形变                                                                                                                                      C、细线套受拉力产生形变                                                             D、使橡皮条在某一方向上伸长到某一长度．                                                                                                                                                                                                                                                        答案：F′，F；力的平行四边形定则．D

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