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一、选择题:本大题共13小题;每小题2分,共26分。在每小题给出的四个选项中,只有一项是正确的。 1.一颗在地球表面附近的人造卫星绕地球作匀速圆周运动,已知地球半径为R,地面上的重力加速度为g,则此人造卫星的速度大小是: A.(gR)~(1/2).B.1/2~(2gR)~(1/2). C.(2gR)~(1/2).D.1/2(gR)~(1/2). 2.下列叙述中正确的是: A.原子核的质量数一定等于它的核电荷数。 B.氢原子从定态n=3跃迁到定态n=2,再从定态n=2跃迁到定态n=1,则后一次跃迁辐射的光子的波长短。 C.U238衰变成钍234,它一定是β衰变。
First, the multiple-choice questions: The title of a total of 13 small questions; each question 2 points, a total of 26 points. Of the four options given in each question, only one is correct. 1. An artificial satellite near the surface of the Earth orbits the Earth at a constant speed. The known radius of the Earth is R, and the gravitational acceleration on the ground is g. The speed of this satellite is: A.(gR)~(1) /2).B.1/2~(2gR)~(1/2). C.(2gR)~(1/2).D.1/2(gR)~(1/2). 2. The correct thing in the narrative is: A. The mass of the nucleus must be equal to its nuclear charge. B. The hydrogen atom transitions from the steady state n=3 to the stationary state n=2, and then from the stationary state n=2 to the stationary state n=1, the wavelength of the photon irradiated by the latter transition is short. C.U238 decays to 钍234, it must be β decay.