问题 填空题

如图11为我国自行生产的”红旗-盛世”品牌小轿车, 该车重为1.73×104N,整车质量1730    ,车高1.485       ,当它以60Km/h的速度在水平路面上匀速行驶时受到的牵引力为2000N,那么汽车受到的阻力为            N;当它停在水平路面上时,它受到的支持力为           N。

答案

kg 、m20001.73×104

考点:

专题:计算题;应用题.

分析:(1)已知车重,根据m=计算出实际质量的大小,比较可得质量单位;根据平时对车高度的认识确定车高的单位;

(2)在水平路面上匀速行驶的汽车,在水平方向受到牵引力和阻力的作用,二力是平衡力;当它停在水平路面上时,在竖直方向受重力和支持力作用,二力是平衡力.

平衡力的条件:大小相等、方向相反、作用在同一条直线上、作用在同一个物体上.

解答:解:(1)m===1.73×103kg,因此车的质量为1730kg;平常我见到的车大约为1.5m,因此车高1.485m;

(2)在水平路面上匀速行驶的汽车,在水平方向受到牵引力和阻力的作用,二力是平衡力,因此汽车受到阻力的大小等于汽车受到牵引力的大小,故阻力为2000N;

当它停在水平路面上时,在竖直方向受重力和支持力作用,二力是平衡力,因此汽车受到的支持力等于重力的大小,故支持力为1.73×104N.

故答案为:kg;m;2000;1.73×104

点评:本题考查学生对长度的估算、重力的计算公式以及二力平衡条件的理解和运用;属于基础性习题,掌握基础知识很重要.

阅读理解

Peer(同龄人)Pressure

Peer pressure is just part of the challenges in life.   66  If you need further guidance, this article might help you. It provides three effective tips to deal with it:

Be with friends who respect your beliefs

You can go out with people who accept and respect the things you believe in and those who you know you can share your interests with. It is all right to be choosy with friends because you just want what is best for them and you.   67  You are just exhibiting what you know is right and good for both sides. Your friends will understand you for that. They can drag you away from discrimination and you can be confident that they will not leave you for your stand in life.

  68 

When you are driven by so many peer pressures, you can always stay away from it. You can actually decide not to be one of them. When you have decided on it, learn to be firm with your decision.   69 They should know that you cannot be forced to do certain things because you are strong and firm with what you believe in.

Learn how to say no

Learning to say no is one big factor to deal with some pressures from all of your friends. When you are convinced to do something you know that can only destroy you or ruin you, learn to say no.   70 You cannot just say yes to anything. You have a functional mind and you know what is best for you. So learn to say no even if saying no means losing your friends.

A.Don’t blame others.

B.Have a firm decision.

C.You should know how to deal with it.

D.You can always deal with it positively.E. Just be straightforward and say it without hesitation.

F. This does not mean you are being selfish or you are being self-centered.

G. This can make them believe that you cannot just be driven by any other thing.

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