编者：“浮力”这一章历来皆是初中二年级的同学进人物理学习分化最严重的一章，据有关方面对一所普通中学的跟踪调查分析表明，若学习初二物理其余章节的及格率均在60％～90％之间，唯有这一章只有49．6％，高分率与低分率之比，前几章大约是33．7～76．2％，唯独这一章高达10 Editor: The “buoyancy” chapter has always been the most severely divided chapter in the physics learning process for the second grade junior high school students. According to relevant areas, an ordinary secondary school’s follow-up investigation and analysis shows that if you study the rest of the physics chapter II pass The rates are all between 60% and 90%. Only this chapter has only 49.6%. The ratio of high scores to low scores is about 33.7 to 76.2% for the previous chapters. Cap up to 10