题干

“端午节”时,小明坐火车去旅游,下列涉及到的物理知识,分析合理的是(  )

A:打开行驶中的火车车场,遮阳的窗帘飘向窗外,因为窗外空气流速大,压强大

B:火车的铁轨铺设在枕木上是为了增大受力面积,减小压强

C:火车急刹车时,桌子上的水杯向前滑动,是因为速度减小水杯受到的惯性减小

D:小明携带的拉杆式行李箱有两个小轮子,作用是减小摩擦

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答案(点此获取答案解析)

D

同类题3

阅读下面短文,从短文后各题所给的 A、B、C 和 D 四个选项中,选出可以填入空白处的最佳选项。

    A boy from a farmer's family stopped from school due to poverty, and went back farming to1the family. When he grew up to 19 years old, his father died. After that, all the family2 him including his mother and grandma in sickness.

    At first, he 3a pool and wanted to feed fish. But others told him it couldn't be used to feed fish, but only to grow crops. What he could do was to cover the pool and thereafter he became a  4.

    Then he heard raising chickens was a way of making money.  He borrowed some money from relatives and  5  chickens.  6  a flood attacked the town, and after that all the chickens got sick and        almost  7. His mother could hardly 8  it and died in the gloom.

    He 9the businesses of making wine, fishing or even digging embrasures (炮眼) on the cliff for others.

    When he was 35, he had no wife, no money, but only lived in a house made from earth which would 10in any storm. But he still wanted to 11 . He borrowed some money to buy a truck. But when he   drove it on the road after a short while, he had an  12  and broke his leg. He became crippled. Everyone said he was  13 .

    But later he became a boss, who owned a capital of 200 million. Now lots of people know his past and his business experiences. A journalist made a(n) 14with him.

    “Why do you  15after so many failures?”

    He was sitting in front of a broad table and just had finished a cup of water. Then he held the16cup in hand and asked, “If I loose my hand, what will happen to this cup?”

    “Broken!” answered the journalist.

    He 17his hand and the cup fell to the floor, with a bang sound, but not 18.

    “Even if ten people were there they would believe it was broken. But, it isn't a(n)  19cup. It is made of  20.”