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试题考生注意: 1: 全卷共七大题。 2:第五至第七各题要求写出主要的文字说明、方程式和演算步骤。只写出最后答案,而未写出主要演算过程的不能得分。有数值计算的题,答案中必须明确写出数值和单位。一、本题中每小题给出的几个说法中,有一个是正确的。把正确的说法选出来,并将正确说法前的字母填写在题后方括号内。填写在方括号外的字母,不作为选出的答案。答错的,不答的,都得0分。(1)电梯内有一个物体.质量为m,用细线挂在电梯的天花板上,当电梯以g/3的加速度竖直加速下降时 (g为重力加速度),细线对物体的拉力为:[ ] A.2/3mg B.1/3mg C.4/3mg D.mg(2)一个人站在阳台上,以相同的速速v_0分别把三个球竖直向上抛出、竖直向下抛出、水平抛出,不计空气阻力,则三球落地时的速率:[ ] A.上抛球最大。B.下抛球最大。 C.平抛球最大。D.三球一样大。(3)两物体A和B,质量分别为m_1和m_2,互相接触
Question candidates Note: 1: The volume of a total of seven questions. 2: The fifth to seventh questions require the writing of the main text descriptions, equations, and calculation steps. Only the final answer is written, and no score can be scored without writing the main calculation process. For numerically calculated questions, the values and units must be explicitly written in the answer. One of the few arguments given in each question in this question is correct. Select the correct statement and fill in the correct letter before the question. Letters that are enclosed in square brackets are not considered as selected answers. Those who answered the wrong answer did not score 0 points. (1) There is an object in the elevator. The mass is m, and is hung on the ceiling of the elevator with a thin line. When the elevator accelerates and descends with the acceleration of g/3 (g is the acceleration of gravity), the pulling force of the thin line on the object is :[ ] A.2/3mg B.1/3mg C.4/3mg D.mg(2) A person stands on the balcony and throws the three balls upright vertically with the same speed v_0 Throw downwards and throw it horizontally, excluding air resistance, then the rate at which the three balls land: [] A. The maximum amount of thrown ball. B. Toss the ball the most. C. Flat toss is the biggest. D. The same three goals. (3) Two objects A and B, masses m_1 and m_2, respectively