题干

长沙地铁2号线已开通,据介绍,地铁2号线列车采用的自动保护系统让列车在规定速度内运行,当列车速度超过最高安全速度时,系统会指令列车停下来.为保证停下来时不会追尾和碰撞,如前方有车已停,后方车的自动保护系统就会接收到减速甚至停车的信号.遇紧急刹车时,列车在250米距离内,车速可由80公里/小时降为零.列车客室照明采用节能环保的LED照明方案.照明设备的辅助供电系统安装于列车的车头和车尾,能提供380伏的交流电源.如有紧急情况发生,在电网断电的情况下,蓄电池的紧急照明能提供至少半小时的光亮.另外,每节车厢有两个高清监控摄像头,列车驾驶员可通过驾驶室的监控装置,观察到车内发生的所有情况.文中信息所含物理知识


文中信息

所含物理知识

示例

列车在规定速度内运行

防止惯性现象造成危害

1

节能环保的LED照明方案


2


电磁波传递信息

上一题 下一题 0.0难度 选择题 更新时间:2019-03-17 01:27:14

答案(点此获取答案解析)

解:低碳节能的LED,即是发光二极管,制作发光二极管的核心材料就是半导体材料,节省电能;

系统会指令列车停下来,指令是通过电磁波传递信息;

故答案为:节省电能;系统会指令列车停下来.

同类题4

阅读下列短文,根据短文信息完成文后表格,每空一词。

    This week, our topic is pollution. What are the answers to all of our pollution problems? We asked two experts to give their views.

    ◇Forest Smith is a member of Green First, an environmental group.

    Our future on the Earth looks very bad. We are dumping waste on our land. We can't breathe the fresh air. The sea is polluted too.

    I visited some relatives recently in a small village. They grow their own food and cycle everywhere. They are not wealthy, but they are happy and healthy.

    We must close the factories producing useless products. That will reduce rubbish and air pollution. We must recycle more, give up all cars, and improve public transport.

    A big problem is overpopulation in big cities. We must give up big cities and factories, and go back to a simple way of life.

    ◇John Green is a scientist at a university.

    Things are not as bad as Forest says. We'll have a bright future. We don't need to give up cars but we need to invent better, cleaner engines.

    This won't stop the problem of traffic jams. So we need better public transport. We should also recycle more.

    But some things are getting better. My sister returned last month after living abroad for five years. She said, “Our old neighbourhood doesn't look the same as before-it is cleaner and greener now.”

    In a word, science has brought many improvements to our life.

Forest Smith: A member of an ____ group

Our future on the Earth looks bad.

◇We're ____ waste on our land

◇The air can't be ____ in.

◇People have polluted the sea.

◇The population in ____ cities is very large.

What we can do

____  some factories will reduce rubbish and air pollution.

◇We must recycle more and ____ the public transport better.

Conclusion: We must go back to a simple way of life

John Green: A   ____ at a university.

We still have a   ____ future.

◇We ____ better and cleaner engines because we can't give up cars.

◇We also need better transport and to recycle more.

Conclusion: Life has been ____ a lot because of science.