Sun, Nov 04, 2007 - Page 14 News List

Sunday Science: Wicked-water trick 週日科學: 超炫的「水把戲」

Welcome to Sunday Science! Every Sunday 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 to always ask a grown-up's permission before trying out an experiment.

Wicked-water trick


Amaze your friends and family with this cool water trick. It works best with two people. This trick needs a bit of practice, and until you get the hang of it, is best done in the sink.

What you will need:

Two identical jars (if you don't have two exactly the same, two with the same size mouth will be fine)



Food coloring

Some thin cardboard (index cards or shiny cardboard work best), cut into pieces large enough to cover the mouth of the jars, and leave an extra 2cm edge.

A spoon (to stir the solutions with)

■ Fill one jar (Jar A) three-quarters full with warm tap water. Add a heaping teaspoon of salt and stir well, until the salt has dissolved. Add a couple of drops of red food coloring.

■ Fill the other jar (Jar B) three-quarters full with warm tap water. Add a couple of drops of blue food coloring. Stir.

■ Now carefully top off Jar A until the water reaches the brim. It must be as full as it can be without spilling.

■ Do the same with Jar B.

■ Take a piece of the cardboard. Place it on the top of Jar A. Gently tap the surface of the cardboard. This will create a seal between the cardboard, water and mouth of the jar.

■ This is the tricky part! Jar A is now sealed. If you pick it up quickly and turn it upside down, it will stay sealed. If you are too slow, or tip the jar, the seal will break, water will go everywhere, and you'll have to refill Jar A. Be confident and fast.

■ When you have Jar A upside down carefully place it on top of Jar B. You are making a seal with Jar B, so make sure that the mouths of the jars match.

■ Get your friend to hold on to the bottom jar and slowly slide out the piece of cardboard. What happens? What color is your water?

Science Journal 科學日誌

What happens if you add salt to water? What do you know about saltwater? Where can you find a lot of saltwater? Do you think that saltwater is heavier or lighter than plain water?


■ Empty out the jars. Now refill the jars in the same way. Repeat the trick, but this time, seal Jar B, turn it upside down and place it on Jar A.

■ When you are confident in tipping the jar upside down without breaking the seal, you could move the trick into a large baking pan instead of the sink. That way you can show more people at a time. Be careful that you do the trick in the kitchen though, the colored water might stain soft furnishings.

(Catherine Thomas, staff writer)









■ 將一個瓶子(A瓶)倒入四分之三溫的自來水,再加入滿滿一匙的鹽巴,並攪拌均勻至鹽巴完全溶解在水中。接著,滴入數滴紅色色素,攪拌均勻。

■ 將另一個瓶中(B瓶)倒入四分之三溫的自來水。加入數滴藍色色素,攪拌均勻。

■ 接著,非常小心地將A瓶裝滿水直至瓶口邊緣,一定要滿到幾乎要溢出來那麼滿的水。

■ 在B瓶重複上個步驟。

■ 拿一片紙卡,將它放在A瓶瓶口,非常小心地輕拍一下紙板表面,這會讓這片紙卡、水,和瓶口完全密合。

■ 這就是這個實驗微妙的部份。A瓶目前已經完全密封了,如果你很快地將它拿起並翻轉過來,它還是會保持密封。如果你動作太慢或是將瓶子斜放了,就會破壞了密合,水就會灑得到處都是了。這樣的話,你就必須重新做一次A瓶了。所以在翻的時候,你要對自己有信心,動作快。

■ 當你成功地將A瓶翻轉過來之後,將它小心地放在B瓶之上。你將要把A瓶和B瓶密合,所以你要確認兩個瓶口有對齊。

■ 請你一個朋友幫你拿好下面的瓶子,並且慢慢地將紙板抽走。結果會發生什麼變化?你的水是什麼顏色的?

■ 將兩瓶水倒掉,重複1至4步驟裝滿兩個瓶子。這次,我們要試著讓B瓶放在A瓶之上。

■ 當你有自信可以將B瓶翻轉過來不會打翻的時候,你可以從水槽換到一個夠大的平底鍋中來做這個實驗。這樣的話,你就可以同時表演這個實驗給更多人看了。但你最好還是在廚房來實驗這個小把戲,免得水灑出來會將家裡的陳設品染色。(翻譯:袁星塵)

Next week 下週預告

For next Sunday's experiment you will need the following special items: A large empty soda bottle and several balloons (large).



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