1.B
解释 A.虽然力相等 但因为质量不等 所以位移不等 。B.没有外力 只有弹性势能和动能的转换。 C.受力相等,质量不等,加速度定然不等。D.初速度都为零,加速度不等,速度定然不等。
2.AD
解释 A,正确。B,应该是A的说法。 C,外力做功应该是mgh +1\2mv²。D动能定理:合外力做功等于动能的变化量。
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忘了
1B 弹簧对两个小球组成的系统机械能守恒,物体所受力为内力,故系统机械能守恒。
2 A 卫星克服重力做功为mgh ---克服重力做功及为重力做工---mgh
D D合外力对卫星做功为1\2mv² 合外力时物体机械能转化的量度(动能定理)
3BD p点应是合外力0点,及物体加速度为0,但物体有初速度,所以速度最小卫星经过P时动能最小(p为两轨道的交界点,故为合外力0点)
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