题干

在探究“阻力对物体运动的影响”时,让同一小车从同一斜面的顶端下滑到底端,使小车以相同的速度分别在棉布表面和木板表面上运动,小车滑行的距离如图所示:

(1)当小车从斜面顶端下滑到底端过程中,小车的重力势能转化为____ 和内能。
(2)当小车在水平木板表面上运动时,受到的一对平衡力是____ 。(填选项前的字母)
      A.小车受到向前的惯性力和木板对小车的阻力
      B.小车受到的重力和小车对木板的压力
      C.小车受到的重力和木板对小车的支持力
(3)实验中可以看出,去掉木板上的棉布后,运动的小车所受的摩擦力减小,向前滑行的距离变大。小车所受摩擦力减小的原因是____ 。
(4)在大量类似实验基础上,牛顿等科学家经过进一步推理而概括出了著名的牛顿第一定律。它是人们公认的物理学基本定律之一,在实际生活中有着   广泛的应用。
一架在空中水平向右匀速直线飞行的飞机上,自由落下了一颗炸弹。下列给出了几种炸弹落地前与飞机位置关系的情形,如图所示。请你认真分析后作出正确的选择:
①不计空气对炸弹的阻力,炸弹与飞机的位置关系为____ 图。
②实际上,由于空气阻力的存在,炸弹与飞机的位置关系为____ 图。

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答案(点此获取答案解析)

动能,C,(压力一定)接触面粗糙程度减小,乙,甲

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    Growing up in Wyoming,everyday life was an adventure—I spent my time camping,and exploring mountains. When I was little,my mom became the state's first female U.S. Marshall.I'll never forget how the local newspaper praised her for her success in a field that's traditionally run by men.Under her influence,I made up my mind to achieve something great.Now,I've become famous for sailing,a sport often considered "a man's world".

    Sailing is considered a hard-to-break-into sport.And,generally,there are only two ways to get into it—either through a strict sailing education that leads to experience or by growing up on the water and racing in the Olympics. Most of my teammates became professional sailors in one of these two ways but I skipped both.

    In the summer of 2008,I went to St.Croix through a college internship(实习)program focusing on educating locals about HIV and AIDs.There,I discovered my love for sailing.Then,SCA,a global hygiene(卫生保健)company, made the decision to support an all-female team,and when they began accepting applications,I knew it was the chance of a lifetime.I made it my task to become a part of the team.Even when it seemed like there were no positions left,I never gave up.

    After a stressful,two-year application process,I finally got the call.I moved to Lanzarote in the Canary Islands and began training with the team immediately.The process was physically,mentally and emotionally exhausting,but I finally achieved my goal.I sailed in the "Everest of sailing" with only six years' experience.Later,there was an all-female team competing,and I was lucky enough to be a part of it.

    As women,we need to approach our dreams as if we deserve to achieve them as much as men,because we do. There are plenty of professions,including sailing,in which women are absent or have a minor presence—but that's not because they shouldn't be there.We need to push the boundaries and focus on obtaining our goals and passions,no matter how unobtainable and challenging they may seem.