题干

如图所示,在研究平抛运动时,小球A沿轨道滑下,离开轨道末端(末端水平)时撞开轻质接触式开关S,被电磁铁吸住的小球B同时自由下落.改变整个装置的高度H,做同样的实验,
发现位于同一高度的AB两个小球总是同时落地,该实验现象说明了A球在离开轨道
后(  )

A:水平方向的分运动是匀速直线运动

B:水平方向的分运动是匀加速直线运动

C:竖直方向的分运动是自由落体运动

D:竖直方向的分运动是匀速直线运动

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答案(点此获取答案解析)

C

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    Every city, in fact, can be felt by its warmth-not in terms of its natural climate but its human touch.

    About twenty years ago, I arrived in Australia. Searching for a place in a map in the street, I was approached by an elderly man who asked “How are you? Are you lost? How can I help you?”, which really impressed and warmed me. Another time, as I was pushing my bike on the sidewalk one night, a young lady shouted to me: “Carry me please” and then jumped onto my bicycle. While we had a little chat, she got where she wanted and hopped off my bike with “Thanks, bye!” At that moment, I had a sense as much of pleasant surprise as of “being trusted”.

    Still in Australia, two of my friends decided to hitch(搭便车)their way to Sydney in order to save money. A young driver stopped, and luckily he was also going to Sydney, so he let them in and even allowed them to drive while he went to sleep on the back seat. About eight hours later, they arrived and he woke up. Saying thanks to each other, they went their separate ways.

    In my opinion, no matter how developed and advanced it is, if in general a place presents itself with a cold and indifferent(冷漠的)face to people, especially to strangers, even keeping them highly alert(警惕的)not to be cheated all the time, can perhaps hardly be classified as a land of civilization(文明). In a sense, the attitude towards strangers that the people have in the city mirrors its warmth.