Sun, Aug 19, 2007 - Page 14 News List

Sunday Science: Earthquake! 週日科學:地震!

By Catherine Thomas  /  STAFF WRITER

Earthquake!

PHOTO: CATHERINE THOMAS, TAIPEI TIMES

Welcome to Sunday Science! Every Sunday during the summer, we're going to guide you through some cool experiments that you can do at home. It's a good idea for you to keep a record of what you do in a Science Journal. That way you can record what you learn, compare results and maybe use them to design new experiments! Have a look at the Science Journal box for some ideas to get you started. Remember always ask a grown-up's permission before trying out an experiment.

歡迎閱讀《週日科學版》!在暑假期間,我們每週日都要為你介紹可以在家中進行的有趣科學實驗。你可以在《科學日誌》中記錄自己做了哪些活動,這樣就可以將所學的紀錄下來,比較這些結果,也許還可以利用它們來設計新的實驗!先看一下《科學日誌》的點子再開始吧。展開實驗之前,記得要獲得大人許可喔!

Have you ever noticed that earthquakes feel differently depending on the type of building you are in at the time? Today's experiment will explain why.

What you will need:

A piece of cardboard (about 30cm by 16cm)

A sheet of construction paper (about 35cm by 50cm). If you don't have any construction paper, you can use stiff paper -- like the cover of a magazine.

Scotch tape

A straw

A ball bearing, BB or other small ball that will fit inside the straw

Scissors

A 30cm ruler

A pen or pencil

- Using your ruler and pencil, divide the paper into five or six strips about 2.5cm wide. The longest strip should be about 50cm. The next should be 8cm shorter, and each succesive strip should be 8cm shorter than the last.

- Carefully cut up the paper so that you have five or six strips.

- Take each strip and tape the ends together to make a circle.

- Stick the circles onto the cardboard, just like in the picture.

- Take the straw and cut a piece 2.5cm long.

- Seal one end of the straw using Scotch tape and a scrap of paper (so that the inside end isn't sticky).

- Put the ball in the straw and seal the other end in the same non-sticky way.

- Attach the straw to the cardboard parallel to your circles.

- Shake the cardboard from side to side, keeping your hands level. Note how the different rings react. Start slowly and then speed up. Don't forget to record your observations in your Science Journal.

你是否注意過地震發生時,你會因當時所在的建築物不同,而有不一樣的感覺嗎?今天的實驗就要告訴你原因!

所需材料︰

一片硬紙板(約三十公分長、十六公分寬)

一張美工紙(約五十公分長、三十五公分寬)如果你手邊沒有美工紙,你可以用硬紙張,如雜誌的封面。

膠帶

一根吸管

小鋼珠、BB槍子彈、或其它可塞入吸管裡的小球

剪刀

一把三十公分長的尺

一枝筆或鉛筆

- 用尺和鉛筆將美工紙劃分成五或六條大約二點五公分寬的細長條。最長的細長條必須五十公分長,下一個長條短八公分,依此類推,接下去的每長條都陸續比上一長條短八公分。

- 小心地把紙裁成剛剛分好的五或六等份細長條。

- 拿起每一細長條並將兩端用膠掉貼起來,做成一個環狀物。

- 將這些環狀物依照圖示黏到硬紙板上。

- 拿起吸管並將它裁成二點五公分長。

- 將吸管的一端用膠帶和小紙片封起來。(如此一來,膠帶的內側才不會黏黏的。)

- 把小鋼珠塞進吸管裡,並且將吸管的另一端用相同的方法封好。

- 將你的吸管平行環狀物,固定在硬紙板上。

- 手保持水平,搖晃你的硬紙板。注意這些環狀物不同的變化。一開始搖慢一點,然後加快速度。別忘記將你的觀察紀錄到你的《科學日誌》裡。(翻譯︰泰德)

What's the Science? 科學原理

The ball hitting the end of the straw shows the frequency of the vibrations you are creating. The rings resonate at more than one frequency each. The largest ring begins to resonate first because it has the largest mass (and so it has a low resonant frequency) and because it is the least stiff of the rings (also giving it a low resonant frequency). An earthquake's frequency (and the direction) will affect how each building reacts. Of course, height is not the only factor. If a building is built well, then the "stiffness" will be increased, so lower frequencies don't affect it as much. So two buildings of the same height can have different reactions in an earthquake.

當小鋼珠撞擊吸管的一端時,其實你正在製造振動頻率。這些環狀物各自有不同的振動頻率。最大的環狀物最先開始共振,因為他的質量最大(它的共振頻率也因此較小)同時,因為它是所有中最不堅硬的,所以它的共振頻率比較小。每棟建築物也因此由於地震頻率還有其搖晃的方向不同而有不同的反應。當然,建築物的高度並不是唯一取決的因素。如果一棟建築物蓋的夠穩固的話,它的「堅硬度」就會增加,如此一來,低頻率的影響就不會這麼大。所以兩棟相同高度的建築物對同一個地震可能會有不同的反應。

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