试题与答案

在“验证力的平行四边形定则”的实验情况如图甲所示,其中A为固定橡皮筋的图钉,O为

题型:实验题

题目:

在“验证力的平行四边形定则”的实验情况如图甲所示,其中A为固定橡皮筋的图钉,O为橡皮筋与细绳的结点,OB和OC为细绳.图乙是在白纸上根据实验结果画出的图.

(1)如果没有操作失误,图乙中的F与F′两力中,方向一定沿AO方向的是___    。 

(2)在实验中,其中的三个步骤:

①在水平放置的木板上垫一张白纸,把橡皮条的一端固定在木板上,另一端拴两根细线,通过细线同时用两个测力计互成角度地拉橡皮条,使它与细线的结点到达某一位置O点,在白纸上记下O点和两测力计的读数F1和F2.

②在纸上根据F1和F2的大小,应用平行四边形定则作图求合力F.

③只用一只测力计通过细绳拉橡皮条,使它的伸长量与两测力计拉时相同,记下此时测力计的读数F′和细绳的方向.

以上三个步骤均有错误或疏漏,请指出:

①中是______________________;

②中是______________________;

③中是______________________.

答案:

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