’99高考物理第22题,源于’97物理高考科研测试第20题,只是情境较为新颖,立意设问更趋合理。下面结合具体试题作一讨论。一、科研测试题情境略简、设问求解略有不便例1.(’97物理高考科研测试第20题)在光滑水平面上有一质量为1kg 的木块,原来静止于 O 点。现用大小为1N 的水平向东的恒力F_1推它,经过2s 后换成大小仍为1N,而方向为水平向北的水平推力 F_2推它,再经2s 后,换成大小仍为1N 的水平推力 F_3推它,最后使木块静止在某一地点 A。则恒力 F_3作用的时 The 22nd title of the ’99 college entrance examination physics was derived from the 20th issue of the ’97 physical college entrance examination research test, except that the situation was more novel and the intention to set up was more reasonable. The following is a discussion of specific questions. First, the scientific research test case is slightly simplified, and the solution to the questioning is slightly inconvenient. (1) The wooden block with a mass of 1 kg on the smooth horizontal surface was originally stationary at the O point. Now push it with the level of 1N to the eastward constant force F_1, change the size to 1N after 2s, and push it with the horizontal thrust F_2 horizontally to the north, and then change the size to 1N after 2s. The horizontal thrust F_3 pushes it, finally making the block stand still at a certain point A. When constant force F_3 acts