歡迎閱讀《週日科學版》！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！
This week we're going to make a Cartesian diver, which is an eyedropper that you can make sink by pressing the sides of a soda bottle.
What you will need:
PHOTO: MICHAEL KEARNEY, TAIPEI TIMES
A clear two-liter soda bottle (with the cap)
An eyedropper
Water
A small coin (optional)
Tape (optional)
▲ Completely fill the soda bottle with water.
▲Place the eyedropper into the soda bottle. Put enough water into the eyedropper that it just barely floats (but you'll need to leave some air in it). If the eyedropper floats even when it's full of water, you'll need to use tape to attach a coin or another object to it to weigh it down.
▲Put the cap on the soda bottle.
▲ Squeeze the sides of the soda bottle. The eyedropper should sink. When you let go of the bottle, the eyedropper should float. (MICHAEL KEARNEY, STAFF WRITER)
本週我們要來做「浮沉子」實驗，實驗中你可以藉由按壓汽水瓶瓶身讓滴管下沉。
所需材料︰
一個乾淨的兩公升汽水瓶（附瓶蓋）
一支滴管
水
一枚小硬幣（可有可無）
膠帶（可有可無）
▲將汽水瓶完全裝滿水。
▲將滴管放入汽水瓶中，在滴管中裝入適量的水，使它正好漂起（但你得在滴管中留一點空氣），若滴管裝滿水時還浮在水面上，你就得用膠帶黏一枚硬幣或其他物品在滴管上，使它增加重量下沉。
▲將汽水瓶蓋子蓋上。
▲擠壓汽水瓶身，滴管應該會下沉，當你鬆手時，滴管會浮上來。（翻譯 �袁星塵）
What's the science? 科學原理
Boyle's law is a law about gases. It states that if you increase the pressure on a gas, its volume decreases. This is like if you were to squeeze a balloon, the pressure of the air inside the balloon increases while the volume of the air decreases. When you squeeze the bottle, the pressure inside it increases. That forces some water into the eyedropper, which decreases the volume of the air.Density equals mass divided by volume (density = mass/volume). Decreasing the volume increases its density.When the density of the eyedropper and the water and air inside it is greater than that of water, it sinks. When you stop squeezing the bottle, the pressure decreases and the eyedropper floats. It's important to remember that the mass of the air in the eyedropper doesn't change during this experiment.
波以耳定律是關於氣體的定律，該定律說明若增加氣體的壓力，氣體的體積就會變小，這就像你若擠壓一個氣球，氣球內空氣的壓力增加，體積卻變小。當你擠壓瓶子時，瓶內的壓力增加，迫使一些水流入滴管，因此減少了空氣的體積。密度等於質量除以體積（密度＝質量÷體積），當體積減少，密度就會增加。當滴管及管內的水和空氣的密度比水的密度大時，滴管就會下沉；當你停止擠壓汽水瓶，壓力減小，滴管就會浮起。請特別注意，滴管內空氣的質量在實驗中並沒有改變。
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