题干

阅读以下材料,回答下列问题:

我国瓦良格号航母于2012年1月8日进行了第四次出海试航并顺利返航.瓦良格号航母的满载排水量为67500t,4台蒸汽轮机共提供约1.5×105kW的动力,最大航速30节(1节=1海里/小时),航母上安装有卫星通讯天线、有源相控阵雷达等设备,配备近防武器系统和各型舰载机.

(1)航母上的雷达发现敌方的军事目标,是利用了____ (选填“电磁波”或“超声波”),它____ (填“能”或“不能”)在真空中传播.

(2)蒸汽轮机利用重油(原油提取汽油、柴油后的剩余重质油)做燃料,通过锅炉把水加热成蒸汽,由蒸汽推动蒸汽轮机转动.重油是____ (选填“可再生”或“不可再生”)能源;蒸汽轮机工作时将燃料燃烧获得的____ 能转化为机械能.

(3)该航母满载行驶受到的浮力____ N.若航母以最大航速航行100海里,消耗120t重油,则行驶时间为____ h;完全燃烧120t重油可产生____ J的热量,4台蒸汽轮机的效率约为____ .(重油的热值q=4×107J/kg,g取10N/kg)

(4)某舰载机在静止的航母上,通过弹射装置获得一定的初速度后,在水平跑道上以6×106W的恒定功率沿直线加速,行驶过程中所受阻力不变,运动的速度v与时间t的关系如图甲所示,飞机运动过程中受到的阻力是____ N.舰载机机翼的横截面设计成如图乙所示的形状,是利用了在气体中流速越大的地方压强越____ 的原理,为飞机提供升力.为了获得更大的升力,飞机起飞时应让飞机____ (选填“逆风”或“顺风”)起飞.

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答案(点此获取答案解析)

电磁波,能,不可再生,内,6.75×108,3.33,4.8×1012,37.5%,6×104,小,逆风

同类题2

阅读下面短文,从短文后的五个选项中选出能填入空白处的最佳选项。每个选项只能用一次。

    Is there anything worse than that? You bravely raise your hand to answer a question, but your teacher just point out that you’re wrong. What a shame! What could the teacher make you suffer (忍受) this?

    Relax. ____. Your teacher isn't calling you out to humiliate (使丢脸) you, but rather out of concern for you and your education.

    Having all your classmates come to know your weak points can be pretty hard, so how can you get past the shame and recognize class participation as a learning opportunity?

    Get out of your comfort zone. Terrill Schumaker, a teacher, explains that “the more you speak out, the more you learn how to grow and build confidence. ____

    Realize it's not a big deal. ____. People aren’t going to care all that much. “If I'm wrong or make a stupid point, then people laugh at me, but life moves on” says Grade 12 Kristen Wesenberg. Besides, everybody makes mistakes, and you can't be perfect all the time.

    ____. Of course it takes courage (勇气), but as Wesenberg says, ―What's the point of living in fear?‖ You won't learn anything if you are not brave enough.

    Use the experience as a learning tool. Wesenberg advises asking teachers why you're wrong so they can explain and you can learn.____. If you're wrong now, at least you won't be wrong in your next test!

A. Be brave in class

B. Trust your teacher instead

C. Use class time as a mini—test

D. And it's not the end of the world

E. Then you can live an exciting life