问题 选择题

关于力和运动的关系,以下说法中正确的是

A.物体受到外力作用,其速度一定增大

B.物体受到不变的合外力的作用,其加速度一定不变

C.物体做曲线运动,说明其受到合外力为变力

D.物体做匀速圆周运动,其受到的合外力为不变的力

答案

答案:B

:当合外力与速度成钝角的时候速度减小,由牛顿第二定律可知物体受到不变的合外力的作用,其加速度一定不变,平抛运动中合外力为重力,是恒定不变的,匀速圆周运动中合外力时刻指向圆心

阅读理解

British researchers have found that children’s IQ predicts their probability of becoming vegetarians (素食者) as young adults.

Recent studies suggest that vegetarianism may be associated with lower cholesterol (胆固醇), reduced risk of overweight and heart disease.

“We know from other studies that brighter children tend to behave in a healthier fashion as adults—they’re less likely to smoke, less likely to be overweight,less likely to have high blood pressure and more likely to take exercise.” lead author Catharine Gale said, “This study provides further evidence that people  with a high IQ tend to have a healthier lifestyle.”

In the study, Gale’s team collected data on nearly 8,200 men and women aged 30, whose IQ had been tested when they were 10 years of age.

“Children who scored higher on IQ tests at age 10 were more likely than those who got lower scores to report that they were vegetarian at the age of 30.”Gale said. 

The researchers found that 4.5 percent of participants were vegetarians. Of these, 2.5 percent were vegan, and 33.6 percent said they were vegetarian but also ate fish or chicken.

There was no difference in IQ score between strict vegetarians and those who said they were vegetarian but also ate fish or chicken,the researchers added.

One expert said the findings weren’t the whole answer,however.

“We don’t know the beliefs or attitudes of the parents of the children,nor do we know if there was a particular event that led these children to becoming vegetarian in their teens or adulthood.” said Lona Sandon, and assistant professor at the University of Texas Southwestern Medical Center at Dallas.

小题1:From the article,we know that ________.

A.brighter children are likely to become vegetarians when they are ten.

B.people with a higher IQ will not be overweight

C.brighter children are likely to have a healthier lifestyle

D.overweight may cause high blood pressure小题2:What does the underlined word “vegan” in the sixth paragraph mean?

A.Someone who only eats vegetables.

B.Someone who chooses not to eat meat or fish.

C.Someone who likes eating meat and fish.

D.Someone who likes eating vegetables.小题3:This study left some unanswered questions EXCEPT “________”.

A.Did the vegetarian children grow up in a family with a vegetarian parent?

B.Did the children eat a primarily vegetarian diet at the age of 10?

C.Were meatless meals regularly served in the participants’ families?

D.Did the vegetarian children really have a high IQ?小题4:The main idea of the passage is that ________.

A.the low IQ children will be unhealthier when they grow up

B.being vegetarians can reduce the risk of overweight and heart disease

C.IQ is important to vegetarians

D.high IQ children are more likely to become vegetarian when they grow up

判断题