在学习万有引力与航天一章时,在遇到求天体共线或连续观察到星球运动时间问题时,很多学生无从下手,不能够画出正确的相对位置关系图,所以找不到各天体之间的相关条件;或者是因为对学生的数学能力要求过高,使很多学生茫然不知所措。对这一类题目,如果换一个参考系去观察,就可以使问题简单化,从而避开繁琐的数学过程,就这一问题进行讨论。 When studying universal time of celestial bodies or continuously observing the problem of planetary movement time, many students can not start their own work and can not draw the correct relative position diagram, so they can not find the space between the celestial bodies Of the relevant conditions; or because of the students’ mathematical ability is too high, so many students at a loss overwhelmed. For this type of topic, if we look at a reference frame, we can simplify the problem and avoid the tedious mathematical process to discuss this issue.