问题 选择题

一个质量为10kg的物体放在水平地面上,当受到一个水平推力F1=30N时,其加速度为1m/s2,当受到的水平推力变为F2=60N时,其加速度为(  )

A.6m/s2

B.4m/s2

C.3m/s2

D.2m/s2

答案

物体在竖直方向受力平衡,水平方向受到推力和滑动摩擦力,设滑动摩擦力大小为f.根据牛顿第二定律得

   第一种情况:F1-f=ma1,得f=F1-a1=30N-10×1N=20N

   第二种情况:F2-f=ma2,得a2=

F2-f
m
=
60-20
10
m/s2=4m/s2

故选B

单项选择题 A1型题
阅读理解

I bought a Paul Smith shirt three months ago. For those who don’t know, Paul Smith is an English designer brand.

His shirts cost about 1,000 yuan and upwards. I paid 50 yuan for my colorful shirt from a street vendor in Beijing.

Of course my shirt was a knockoff, a cheap copy of the brand. After a few washes, little balls formed on the surface of the thin material.

Do I care? Not at all. You get what you pay for.

I have to admit I hate shopping. I don’t care enough about spending money on clothes. I have other priorities.

In You Are What You Wear, US writer Jennifer Baumgartner says people’s clothes tell a story about their personality.

She writes: “The clothes you choose to wear provide important information about you as a person: your approximate education level, your income, social status and even your level of self-esteem (自信).” When I started work as an undercover crime reporter, I had to shop for jeans and a hoodie (连帽衫) in order to fit in with a rough and ready (世故的) social group.

I bought the hoodie in a charity shop. My daughters were shocked. They thought I looked bad, but I knew my disguise was perfect.

Elizabeth L. Cline thinks she knows best when it comes to cheap clothes in her book Overdressed: The Shockingly High Cost of Cheap Fashion. She expresses sadness that clothing has been turned into a good that is thrown away after being used once or twice.

She looks down her nose at cheap fashion and longs for the good old days when department stores sold quality clothes at high prices.

I don’t agree. At least people now can choose what to wear without breaking the bank.

小题1:The underlined sentence in the article meant that         .

A.I don’t mind spending money on clothes

B.there’s not much point spending money on clothes

C.it is too much trouble to spend money on clothes

D.I never spend money on clothes小题2:From the text we can infer that the author’s disguise         .

A.immediately won the admiration of his daughters

B.turned out unsuited to his plan

C.proved that clothes can’t show a person’s true personality

D.had something to do with his income小题3:The author mentions Elizabeth L. Cline’s book to         .

A.express his anger at the poor quality of clothes

B.show his disagreement with her idea

C.show his dislike for how people treat their clothes

D.support her attitude toward spending money on clothes小题4:Which of the following might be the best title for the story?

A.The variety of clothes

B.You are what you wear

C.High cost of cheap fashion

D.You get what you pay for