第43/779期初二教案

作者：汤红梅

 

Powerful principle (P6)

Pre-reading

Look and think.

Do you know how to quickly fill a large bag with air? Why?

 

While reading

Physics can be amazing. The same force ( 力 ) that makes airplanes fly can also cool down your bedroom on a hot summer night. This is called Bernoulli’s Principle ( 伯努利定律 ).

cool down : （使）变凉; 冷静下来; 消气; 降温;

翻译：在炎热的夏夜，让飞机飞起来的同样的力量也可以让你的卧室降温。

练习：外面太热了，我们要想办法凉快下来。

 It’s so hot outside, we need to find a way to cool down.

 

Recently, a science teacher’s TikTok video got a lot of attention ( 注意 ). In the video, User Wolf_Science shows how to quickly fill a large bag with air using Bernoulli’s Principle.

fill with：（使）充[挤]满; 使满怀（某种情感等）

翻译：如何用伯努利原理快速地给一个大袋子装满空气。

练习：她的眼眶里饱含着幸福的热泪。

             Her eyes filled with tears of joy .

 

Bernoulli’s Principle is named after Daniel Bernoulli, a Swiss physicist who introduced it in 1738. It says that when fluids ( 流体 ) – liquids and gases – move quickly, they create low-pressure zones ( 低压区域 ). Faster movement means lower pressure. The higher-pressure fluids will rush to fill the low-pressure zone.

name after：以…的名字起名;

翻译：伯努利原理是以1738年瑞士物理学家丹尼尔·伯努利的名字命名的。

练习：许多建筑物都是以著名人物命名的。

              Many buildings are named after famous people.

 

Bernoulli’s Principle is named after Daniel Bernoulli, a Swiss physicist who introduced it in 1738. It says that when fluids ( 流体 ) – liquids and gases – move quickly, they create low-pressure zones ( 低压区域 ). Faster movement means lower pressure. The higher-pressure fluids will rush to fill the low-pressure zone.

rush [rʌʃ] ： v.  猛冲; 急忙送; 赶紧做; 突袭;

翻译：高压流体将涌入低压区。

练习：一位女学生冲进起火的公寓里去救一名儿童。

             A schoolgirl rushed into a burning flat to save a kid's life.  

 

In the video, the teacher blows ( 吹 ) into a large bag 10 times with his mouth. But he can’t fill the bag with air like this. Then, he puts the bag a few centimeters ( 厘米 ) away from his mouth and blows hard one time. The moving air creates a low-pressure zone inside the bag. Air rushes in, filling the bag in just one second!

moving [ˈmuːvɪŋ] : adj.  移动的，运动的; 感人的 ;

zone [zəʊn] : n.  地区，区域; 气候带;

翻译：流动的空气在袋子内部形成一个低压区。

练习：火车运行时请勿上下车。

             Don't try to get on or off a moving train!

 

How does this make an airplane fly? The secret is the shape of the wings. The shape causes air moving over the top of the wing to go faster than the air moving underneath. This creates a low-pressure zone above the wing. Higher-pressure air from below rushes upward, lifting the plane off of the ground.

underneath  [ˌʌndəˈniːθ]  : adv.  在下面，在底下，在下层;

                prep.  在…之下; 在下面; 在…下面;  n.  下部，底部;;

翻译：这种形状使得机翼上方的空气流动速度比下方的空气流动速度快。

练习：底下的空间可用作储藏区。

             The space underneath could be used as a storage area.  

 

lift  [lɪft] : v.  提; 移动; 抬起;

翻译：高压空气从下面冲上来，使飞机离开地面。

练习：他站在那里，胳臂举过了头顶。

              He stood there with his arms lifted above his head.

 

You can put Bernoulli’s Principle to work at home. If your bedroom is full of hot air, you can cool it quickly. Point an electric fan ( 电风扇 ) toward the window, but don’t put it too close. When the fan runs, it will create a low-pressure zone. The hot air will go out the window. Firefighters use this same trick to quickly clear smoke out of a house.

point [pɔɪnt] ：v.  指（向）向; 瞄准; 勾缝; 表明; 强调;

翻译：把电风扇对着窗户，但不要把它放得太近。

练习：他指出那所房子原来所在的地方。

             He pointed to the spot where the house used to stand.

trick  [trɪk] ：n.技巧，窍门;诡计，骗局; 把戏;

翻译：消防队员用同样的方法快速清除房屋内的烟雾。

练习：他们只好想出个计谋骗过岗哨。

              They had to think of a trick to get past the guards.  

 

Post-reading

Can you explain the experiment  in this picture with Bernoulli’s Principle?

Do you know of any other examples?

 

    

Practice

Choose the answer:

1. How does the teacher quickly fill the large bag with air in the video?

By putting the bag a few centimeters away from his mouth and blowing air into it

B. By blowing air directly into it ten times.

C. By creating a low-pressure zone outside the bag.

D. By creating a high-pressure zone in the bag.

 

2. What makes an airplane fly, according to the passage?

A. The shape of its body.

B. The high pressure above its wings.

C. The low pressure beneath the plane.

D. The speed of the air above and below its wings.

 

3. According to the last paragraph, to cool a room, where should a fan be placed?

A. Facing the floor.

B. Facing the ceiling.

C. Facing the room.

D. Facing the window.

 

4. What do we know about Bernoulli’s Principle?

A. It means that faster movement creates high pressure.

B. It is a new discovery.

C. It can be used to clear smoke out of a burning house.

D. It is named after a TikTok user.

 

5. What is the passage mainly about?

A. The difference between high and low pressure.

B. Popular ways to create different pressure zones.

C. An experiment to improve flight safety.

D. An introduction to Bernoulli’s Principle.

 

完成句子。

1. Ambulances ______ (急忙送往) the injured to the hospital.
2. He was stuck in a line of slow-______ (移动的) traffic.  
3. Do not enter the danger ______ (地区)!  
4. I ______ (抱起) the baby out of the chair.
5. She ______ (指向) her finger in my direction.

 

翻译句子。

1. On a clear night, we can see the sky filled with stars.
2. The trick is to pick the animal up by the back of its neck.

 

1. 你可以用扇子帮我把汤降温吗?
2. 这台机器是以它的发明者的名字命名的。
3. 硬币滚到了钢琴底下。

 

参考答案：

1. 本题为细节判断题。由he puts the bag a few centimeters away from his mouth and blows hard one time可知，A选项与之相  符，CD选项与文意相反，故选为正确答案。
2. 本题为理解判断题。由本段可知飞机飞行的秘密在于机翼的形状，其上下的空气流动形成了不同的气压区—其上为低压区，其下为高压区，从而使得飞机升空飞行，所以最根本的原因来自机翼上下空气的流动速度，所以正确答案为D。
3. 本题为细节信息题。由Point an electric fan toward the window, but don’t put it too close可知，为了给房间降温电风扇应该放置在对着窗口的位置，因此正确答案为D选项。
4. 本题为细节判断题。由Firefighters use this same trick to quickly clear smoke out of a house可知，这一原理得以被消防员应用于火灾房屋的驱烟救助中，因此正确答案为C选项。
5. 本题为主旨归纳题。由文意表述可知文中通过几个实例直观地介绍说明了伯努利定律的原理以及具体应用，因此正确答案为D选项。

 

完成句子。

1. rushed    2. moving   3. zone   4. lifted    5. pointed

 

翻译句子。

1. 在晴朗的夜晚，我们可以看到繁星满天。
2. 窍门在于抓住动物的后脖颈把它提起来。

 

1. Can you cool down the soup with the fan for me?
2. The machine is named after its inventor.
3. The coin rolled underneath the piano.