问题 选择题

下列关于速度和加速度关系的说法中正确的

A.速度变化量越大,加速度越大

B.加速度的方向就是速度的方向

C.加速度为零时,速度一定为零

D.加速度越来越小,速度可能越来越大

答案

答案:D

题目分析:加速度是表示物体运动速度变化快慢的物理量,与物体的速度、速度的变化无关。速度变化量越大,但由于速度变化的时间不确定,则加速度的大小不确定,所以A选项错误;加速度的方向跟速度变化的方向相同,所以B选项错误;加速度为零时,物体可能做匀速直线运动或出于静止状态,C选项错误;加速度越来越小,若物体做加速运动,物体的速度越来越大,若物体做减速运动,物体的速度越来越小,故加速度越来越小,速度可能越来越大,所以D选项正确。

阅读理解

Do you want to live a happier, less stressful life? Try laughing for no reason at all. That’s how thousands of people start their day at Laughter Clubs around the world — and many doctors now think that having a good laugh might be one of the best ways to stay healthy.

The first Laughter Club was started in Mumbai, India, in 1995 by Dr. Madan Kataria. “Young children laugh about 300 times a day. Adults laugh between 7 and 15 times a day,” says Dr. Kataria, “Everyone’s naturally good at laughing. We want people to feel happy with their lives.” There are now more than 500 Laughter Clubs in India and over 1,300 worldwide.

Many doctors are also interested in the effects of laughter on our health. According to a 5-year study at the UCLA School of Medicine in California, with laughing there is less stress in the body. Laughter improves our health against illness by about 40%.

So, what happens at a Laughter Club? I went along to my nearest club in South London to find out. I was quite nervous at the beginning of the class, to be honest — I wasn’t interested in laughing with a group of strangers, and I was worried about looking stupid. Our laughter teacher told us to clap our hands and say “ho ho ho, ha ha ha,” while looking at each other. However, our bodies can’t tell the difference between fake laughter and real laughter, so they still produce the same healthy effects.

Surprisingly, it works! After ten minutes everybody in the room was laughing for real — and some people just couldn’t stop! At the end of the class I was surprised by how relaxed and comfortable I felt. So if you’re under stress, then start laughing. You might be very pleased with the results!

小题1:The first Laughter Club was started in _____.

A.Britain

B.America

C.Australia

D.India小题2:The writer felt _____ at the beginning of the class?

A.surprised

B.pleased

C.nervous

D.stressful小题3:The people in the club began to laugh for real _____?

A.after ten minutes

B.after ten hours

C.after a few seconds

D.after ten days小题4:Which of the following is true according to the passage?

A.Fake laughter and real laughter are both good for health.

B.40% of the people in Laughter Clubs are good friends.

C.Adults laugh more often than children in a day.

D.Laughing is the best way to prevent illness.

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