问题 选择题

对α粒子散射实验,下列描述正确的是

A.绝大多数α粒子穿过金箔时都会明显改变运动方向

B.少数α粒子穿过金箔时会被反向弹回

C.散射角度大的α粒子受原子核的作用力也大

D.无论散射角度大小,α粒子的机械能总是守恒的

答案

答案:C

分析:明确α粒子散射实验现象以及造成这种现象的原因,正确利用机械能守恒条件判断机械能是否守恒.

解答:解:α粒子散射实验的内容是:绝大多数α粒子几乎不发生偏转;少数α粒子发生了较大的角度偏转;极少数α粒子发生了大角度偏转(偏转角度超过90°,有的甚至几乎达到180°,被反弹回来),故AB错误;

造成α粒子散射角度大的原因是受到的原子核的斥力比较大,故C正确;

α粒子运动过程中受到除重力之外的斥力作用,因此机械能不守恒,故D错误.

故选C.

点评:对于α粒子散射实验要明确其实验现象和结论,了解该实验的历史背景和历史作用.

单项选择题
阅读理解

Every weekend, many Americans drive around looking for things to buy. They are taking part in an unusual kind of outdoor treasure hunt: the yard sale (旧货出售). In some parts of the country, such a sale might be called a garage sale or a moving sale. Whatever the name, the activity is the same. People sell things they no longer want.

The sellers put a paid announcement in a local newspaper. It tells when and where the yard sale will take place. It lists some of the things to be sold. Early in the morning, all the things to be sold are carried out of the house. Then they sit all day waiting for someone to take them home. Usually, the seller puts a price on each object at a yard sale. However, that price can almost always be negotiated (谈判).

Serious buyers also spend time getting ready for yard sales. They collect the newspaper announcements. Then they make lists of the sales they want to attend.

Most people who go to yard sales are not looking for anything special. They might buy an object simply because it costs so little. They enjoy bargaining over prices, even if they may hold their own yard sale to sell all the things they have bought.

To other people, yard sales are simply a way to have fun. In some communities, they are important social gatherings. Other people say yard sales help the environment. Old things are re-used instead of being thrown away.

In any case, yard sales are very popular in America. Hunting for unusual items is a sport for some people. For others, it is a way of life.

59 What can’t you get to know about the yard sales announced in a local newspaper?

A.When to attend the yard sale.

B. Where to attend the yard sale.

C. What is to be sold at the yard sale.

D. The prices of the things to be sold at the yard sale.

60 Before a yard sale, the sellers need to do all the following things EXCEPT ______.

A. putting a paid announcement in a local newspaper

B. bargaining over the prices with the buyers

C. putting the price of each object

D. carrying all the things to be sold out of the house early in the morning

61 Which of the following is NOT true according to the passage?

A. A yard sale can also be called a garage sale or a moving sale.

B. The sellers need to pay for putting an announcement in a local newspaper.

C. The sellers collect the newspaper announcements before the yard sales.

D. The prices for the items to be sold at a yard sale can be negotiated.

62.Which of the following statements is NOT mentioned as the reason why yard sales are very popular in America?

A. People can buy something special at yard sales.

B. People can buy something they really want.

C. People can enjoy bargaining over prices.

D. People regard yard sales as social gatherings.