问题 填空题

如图所示,小明分别用甲、乙两个不同的音叉来研究音叉发声特点,发现第一次甲音叉旁的乒乓球弹得远,第二次乙音叉旁的乒乓球弹得快,这说明第______次的音调低,第______次敲得重;如果音叉的振动小于______Hz,人耳将听不到这个声音.

答案

此题中振动的快慢和振动幅度的大小是用转换法,通过乒乓球来体现的,乒乓球弹得远说明振幅大,响度大,乒乓球弹得快说明频率高,音调高.

(1)第一次乒乓球弹得慢,说明音调低;

(2)第一次乒乓球弹得远,说明响度大,敲得重;

(3)低于20Hz和高于20000Hz的声音,人耳听不到.

故答案为:一;一;20.

单项选择题 共用题干题
阅读理解

阅读理解。

     Martin Frobisher,born in Yorkshire,went to London as a boy to be educated by a relative.

He showed no talent for book learning,so his relative sent him to sea.Before reaching manhood,

Frobisher had been on two voyages to the Guinea Coast.On the second he was captured and

handed over to the Portuguese garrisoning (驻守) Sao Jorge da Mina (now Elmina,Ghana),who

allowed him to return to England.

     By the 1570s,England had largely abandoned hope of finding a Northeast Passage to Asia,

and thoughts turned to the Northwest.Frobisher worked together with Michael Lok,a man of some

wealth and learning.Frobisher's first voyage,in 1576,took him to Frobisher Bay in Baffin Island.  

     English investors (投资者),including Queen Elizabeth,poured money into  Lok's Company of

Cathay.Frobisher sailed again in 1577,this time to ship home what he mistakenly thought was

goldbearing minerals.Lok still felt hopeful and sent Frobisher back in 1578.This time the mariner

discovered the Hudson Strait.He followed the strait for nearly 200 miles,believing it to be a more

promising Northwest Passage than Frobisher Bay.He brought home more dirt and rocks,but English

confidence had gone;Lok went to a debtors' prison and Frobisher sought other employment.

     Frobisher accompanied Sir Francis Drake to the West Indies in 1585~1586.When Philip Ⅱ's

Spanish Armada (无敌舰队) entered the English Channel in 1588,Frobisher's part in the fighting was

successful and he received knighthood (爵士爵位).He died of a wound received near Brest,where

he had been sent to relieve the siege (解除包围).He lived just long enough to be taken back to Plymouth.

1.The underlined word "abandoned" in Paragraph 2 can best be replaced by .

A.kept alive      

B.given up          

C.seen          

D.shared

2.From Paragraph 3 we learn that Frobisher at first        .

A.brought gold to England        

B.discovered a Northeast Passage

C.received strong support          

D.had been put into prison

3.According to the passage,Frobisher died in        .

A.Frobisher Bay    

B.the West Indies      

C.Brest      

D.Plymouth

4.Which of the following shows the right order of the events relating to Frobisher?

a.He arrived in Baffin Island.

b.He voyaged to the Guinea Coast.

c.He went to the West Indies.

d.He discovered the Hudson Strait.

A.b,a,d,c        B.b,c,d,a    C.a,d,c,b     D.a,b,c,d