问题 选择题

如图所示,一薄圆盘可绕通过圆盘中心且垂直于盘面的竖直轴OO′转动.在圆盘上放置一小木块.当圆盘匀速转动时,木块相对圆盘静止.关于木块的受力情况,下列说法正确的是(  )

A.木块受到圆盘对它的静摩擦力,方向指向圆盘中心

B.由于木块相对圆盘静止,所以不受摩擦力

C.由于木块运动,所以受到滑动摩擦力

D.由于木块做匀速圆周运动,所以除了受到重力、支持力、摩擦力外,还受向心力

答案

物体做匀速圆周运动,合力提供向心力,指向圆心;

物体受重力、支持力、静摩擦力,其中重力和支持力二力平衡,静摩擦力提供向心力,向心力是合力,不能说成物体受到向心力;

故选A.

阅读理解

第三部分阅读理解 (共15小题;每小题2分,满分30分)

请认真阅读下列短文,从短文后各题所给的A、B、C、D四个选项中,选出最佳选项,并在答题卡上将该项涂黑。

A

Why You Should Celebrate Your Mistakes

When you make a mistake, big or small, cherish (珍视) it like it’s the most precious thing in the world. Because in some ways, it is.

Most of us feel bad when we make mistakes, beat ourselves up about it, feel like failures, get mad at ourselves.

And that’s only natural: most of us have been taught from a young age that mistakes are bad, that we should try to avoid mistakes. We’ve been scolded when we make mistakes—at home, school and work. Maybe not always, but probably enough times to make feeling bad about mistakes an unconscious reaction.

Yet without mistakes, we could not learn or grow. If you think about it that way, mistakes should be cherished and celebrated for being one of the most amazing things in the world: they make learning possible; they make growth and improvement possible.

By trial and error—trying things, making mistakes, and learning from those mistakes—we have figured out how to make electric light, to paint the ceiling of the Sistine Chapel, to fly.

Mistakes make walking possible for the smallest toddler, make speech possible, make works of genius possible.

Think about how we learn: we don’t just consume information about something and instantly know it or know how to do it. You don’t just read about painting, or writing, or computer programming, or baking, or playing the piano, and know how to do them right away. Instead, you get information about something, from reading or from another person or from observing usually … then you construct a model in your mind … then you test it out by trying it in the real world … then you make mistakes … then you revise the model based on the results of your real-world experimentation … and repeat, making mistakes, learning from those mistakes, until you’ve pretty much learned how to do something. That’s how we learn as babies and toddlers, and how we learn as adults. Mistakes are how we learn to do something new—because if you succeed at something, it’s probably something you already knew how to do. You haven’t really grown much from that success—at most it’s the last step on your journey, not the whole journey. Most of the journey was made up of mistakes, if it’s a good journey.

So if you value learning, if you value growing and improving, then you should value mistakes. They are amazing things that make a world of brilliance possible.

56. Why do most of us feel bad about making mistakes?

A. Because mistakes make us suffer a lot.

B. Because it’s a natural part in our life.

C. Because we’ve been taught so from a young age.

D. Because mistakes have ruined many people’s careers.

57. According to the passage, what is the right attitude to mistakes?

A. We should try to avoid making mistakes.

B. We should owe great inventions mainly to mistakes.

C. We should treat mistakes as good chances to learn.

D. We should make feeling bad about mistakes an unconscious reaction.

58. The underlined word “toddler” in Paragraph Six probably means _______.

A. a small child learning to walk             B. a kindergarten child learning to draw

C. a primary pupil learning to read                     D. a school teenager learning to write

59. We can learn from the passage that _______.

A. most of us can really grow from success

B. growing and improving are based on mistakes

C. mistakes are the most precious things in the world 

D. we read about something and know how to do it right away

判断题