F***t
发帖数: 412 | 1 When it is about the same distance from the Sun
as is Jupiter, a spacecraft on a mission to the outer
planets has a speed that is 1.5 times the speed of
Jupiter in its orbit. Which of the following describes
the orbit of the spacecraft about the Sun?
(A) Spiral
(B) Circle
(C) Ellipse
(D) Parabola
(E) Hyperbola
答案为E。
但我觉得似乎得假设Jupiter的轨道为圆形，或近乎圆形。
因为如果Jupiter的轨道为椭圆形，则在各点的速度不同。
如果飞船速度是Jupiter在其近地点速度的1.5倍，那么
飞船将沿双曲线飞离太阳。
如果是远地点速度的1.5倍，则不一定能飞离太阳。
请指正。 | m*****d
发帖数: 18 | 2 太阳系各个星体的轨道都是园的很小偏离，所以加了这么大速度
必然飞出去，ok?
【在 F***t 的大作中提到】
: When it is about the same distance from the Sun
: as is Jupiter, a spacecraft on a mission to the outer
: planets has a speed that is 1.5 times the speed of
: Jupiter in its orbit. Which of the following describes
: the orbit of the spacecraft about the Sun?
: (A) Spiral
: (B) Circle
: (C) Ellipse
: (D) Parabola
: (E) Hyperbola
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