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题目一质量为8.00×10~4 kg的太空飞船从其飞行轨道返回地面。飞船在离地面高度1.60×10~5m处以7.5×10~3 m/s的速度进入大气层,逐渐减慢至速度为100 m/s时下落到地面。取地面为重力势能零点,在飞船下落过程中,重力加速度可视为常量,大小取为9.8m/s~2。(结果保留2位有效数字)(1)分别求出该飞船着地前瞬间的机械能和它进入大气层时的机械能;(2)求飞船从离地面高度600 m处至着地前瞬间的过程中克服阻力所做的功,已知飞船在该处的速度
Title A mass spacecraft of 8.00 × 10 ~ 4 kg returns to the ground from its flight orbit. The spacecraft entered the atmosphere at a velocity of 7.5 × 10 ~ 3 m / s at a height of 1.60 × 10 ~ 5m from the ground and slowly slowed down to the ground at a velocity of 100 m / s. Taking the ground as the zero point of gravity potential energy, the gravitational acceleration can be regarded as a constant during the course of the spacecraft’s drop, taking the size as 9.8m / s ~ 2. (2 valid figures are reserved) (1) Obtain the mechanical energy of the spacecraft immediately before landing and the mechanical energy of the spacecraft when it enters the atmosphere. (2) Obtain the resistance of the spacecraft from its height of 600m to its anterior moment Work done, known speed of the spacecraft in the area