问题 问答题

S1、S2是两个完全相同的波源,它们发出两列波长均为λ的简谐横波,图中虚线和实线分别代表某时刻这两列波的波谷和波峰.

(1)在空间有很多的加强点和减弱点,其中A、B、M、N、P、Q中是减弱点有______.

(2)根据图中的特征填写下表中的各项(下表中已给出部分物理量,请再根据给出的部分物理量的有关特征填写空缺项)

质  点    P    Q    M    N    A
到S1的距离3.5λ2.5λ
到S2的距离2.5λ1.5λ4.5λ

答案

(1)由图象知P、M为两列波的波谷和波谷相遇的点,A、Q、N为两列波的波峰和波峰相遇的点,这5个点到两波源的路程差为波长的整数倍,都是振动加强的点.只有B点是两列波的波峰与波谷相遇的点,到两波源的路程差为半个波长的奇数倍,则B点的振动减弱.

(2)A点振动加强,由图看出,A点到两个波源的距离相等,都是4.5λ.

质点      P   Q   M   N   A
到S1的距离3.5λ2.5λ4.5λ
到S2的距离2.5λ1.5λ4.5λ
故答案为:B,4.5λ

阅读理解

Hundreds of years ago, life was much harder than it is today.People didn’t have modern machines.There was no modern medicine, either.

Life today has brought new problems.One of the biggest is pollution.Water pollution has made our rivers and lakes dirty.It kills our fish and pollutes our drinking water.Noise pollution makes us talk louder and become angry more easily.Air pollution is the most serious kind of pollution.It’s bad to all living things in the world.

Cars, planes and factories all pollute our air every day.Sometimes the polluted air is so thick that it is like a quilt over a city.This kind of quilt is called smog.

Many countries are making rules to flight pollution.Factories must now clean their water before it is thrown away and they mustn’t blow dirty smoke into the air

We need to do many other things.We can put waste things in the dustbin and do not throw them on the ground,there will be less pollution.

Rules are not enough.Every person must help to fight pollution.

小题1:Hundreds of years ago.life was much harder than it is today because        

A.there were not any modern machines

B.there was no modern medicine

C.both A and B

D.there were not many people小题2:The most serious kind of pollution is         

A.noise pollution

B.air pollution

C.water pollution

D.All the above小题3:From the passage we know that       

A.a few years ago,there was no smog at all

B.today people don’t have to talk to each other in a loud voice

C.we can drink water from the polluted rivers and lakes

D.people are making rules in order to fight pollution

问答题 简答题