如图示是某型号的四轮轿车，车身质量是2000kg. (1)该轿车的尾部_爱下问搜题

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问题计算题

如图示是某型号的四轮轿车，车身质量是2000kg.

(1)该轿车的尾部安装了导流板，如图所示.它的作用主要是在轿车高速行驶时，增加对地面的压力，提高车轮的抓地性能.则导流板横截面的形状是 _____________.

(2)该轿车空车停放在水平路面上时，某同学测得该轿车每个轮胎与地面接触的面积约为100cm²，则此时该轿车对水平路面的压强约为多大(g取l0N／kg)?

(3)该轿车在高速公路上以108km/h的速度匀速前进，发动机的输出功率为120kW，则轿车受到的阻力是多大?

答案

解：(1)B

(2)S=4 S₁=4×0.01m²=0.04m²

F=G=mg=2000kg×10N/kg=20000N

p=F/s=20000N/0.04m²=5×10⁵Pa

(3) P=W/t=Fs/t=Fv

f=F=P/v=120000W/30ms^-1=4000N

阅读理解

Do you have the ability to live cheaply? Now here’s a true story of an American girl，Sarah．
21 Sarah left university，she began to live in New York City on her own．She 22 a job in a publishing house，but the salary(薪水)was 23 $30，000 a year．Her parents thought her life would be hard，but Sarah 24 live on her salary and still saved $5，000 in a year．How was that 25 in one of the most expensive cities in the world?
Cheap living 26 starts with keeping the big cost small．For most people，that 27 housing．So Sarah chose to share a flat with three other friends．Her next biggest cost was 28 ．When she ate out，she went to cheap restaurants． 29 she bought a $9．99 whole chicken at a local restaurant．She then 30 the chicken bones(骨头)home and made soup out of them．Nowadays young people often 31 a lot of money on entertainment(娱乐)．But Sarah said，“I enjoy walking 32 in New York City．I love going to museums and parks．” Did Sarah feel poor 33 cheap living? Not really．She even managed to take two trips，one to the Netherlands， 34 to Portland．
“Don’t think of saving money as something 35 ．It’s a kind of game，”said Sarah．

小题3:A．more than B．less than C shorter than D．higher than

B．interesting

名词解释

绝对年代法