動力裝置始祖︰蒸汽機 在現代的動力裝置發明前，人 類只利用人力或大自然的力量幫忙 推動機械，但產生的動力始終有 限。直至「蒸汽機」的出現，大大提 升了生產力，更導致工業革命的開 始，讓人類正式進入工業時代。 蒸汽機利用在外部燃燒燃料後 加熱的蒸汽，推動活塞產生動力， 屬於外燃機的一種。可是，它起初 只是用於在礦井中抽水的用途，不 僅用途有限，而且效率甚低，並未 能大量應用。 幸好，蒸汽機得以改良後，引 入了分離冷凝器，允許蒸汽在一個 獨立的冷卻室中冷凝，保持氣缸的 熱度，減少了能量損失，只需過往 四分一的煤炭便能達至相同的效 果。當中更引入了連桿和齒輪系 統，將原有機內活塞的直線運動轉 換為旋轉運動，使蒸汽機可以更方 便地驅動各種機械設備，如蒸汽火 車、蒸汽錘等。 汽輪機 不過，要談及更高效應用蒸汽 的裝置，就不得不提及「汽輪機」。 汽輪機更有效地善用蒸汽。它利用 燃料燃燒時產生的高壓蒸汽，透過 葉片擴張，推動轉子旋轉，將熱能 轉化為機械能。它更可用於發電， 甚至推動船舶等大型機械。直到現 時，雖然過往的蒸汽機大多已被淘 汰，但全球的發電廠仍大規模使用 汽輪機產生電力。現時的汽輪機經 改良後，甚至可運用到地熱、太陽 能等可再生能源發電。相信蒸汽的 力量在接下來的世代中仍然不容忽 視，甚至與時並進，扮演重要角色。 現代交通基石︰內燃機 美中不足的是，蒸汽機和汽輪 機需要配置極佔重量和空間的鍋 爐，若要在小小的汽車中加入動力 裝置，則要依靠另一個在人類史上 舉足輕重的動力裝置——「內燃機」。 內燃機通過在引擎中燃燒燃 料，產生高壓氣體，推動活塞轉動 曲軸，轉換為機械能。自從第一具 四行程內燃引擎被發明後，由內燃 機推動的三輪車旋即產生，這個創 新發明更被稱為現代汽車的起點。 四行程內燃引擎運作流程 1. 進氣行程：進氣閥打開，空氣或 空氣與燃油的混合物吸入氣缸。 2. 壓縮行程：進氣閥及排氣閥關 閉，氣缸內的空氣被壓縮。 3. 動力行程：進氣閥及排氣閥仍然 關閉，火星塞以高壓電產生火花 引爆混合氣，產生高壓推動活塞 向下運動。 4. 排氣行程：當活塞再次向上 移動時，排氣閥打開，燃燒 後的廢氣被排出氣缸。 大部分的航空發動機其實也是 內燃機的一種。當中的活塞引擎， 以燃燒推動活塞，從而轉動螺旋 槳。萊特兄弟把四缸活塞引擎應用 到飛機上，實現首次動力飛行，開 啟了航空交通史的新一頁。現時不 少商用大型飛機，例如波音737，會 使用噴氣式發動機，用燃燒燃料產 生高溫高壓氣體，依賴內部渦輪壓 縮空氣並噴射氣流產生推力，大大 縮短了全球飛行時間。 1950年代後跨大西洋飛行時間 從15小時減至7小時，成功使長途飛 行更普及。 資訊科技命脈︰電動機 現時最廣泛應用的動力裝置莫過 於「電動機」，它能將電能轉化為機械 能。 當電流通過導線或線圈時，會在 周圍產生磁場，與外部磁場產生相互 作用，驅動轉子運動，將電能轉化為 旋轉或直線運動的動能。 電動機的能量轉換效率相對較 高，而且沒有燃燒過程，因此不產生 廢氣，更具有噪音低、壽命長、能精 確調節等優點，所以被大量應用到各 種家用電器，甚至電動車、電腦等高 科技裝置當中。 小思考，大智慧 除了文中提及的動力裝置 外，你還知道其他動力裝置嗎？ 參考答案 其他動力裝置如下︰ 1. 由可再生能源推動的動力 裝置： 包括風力機、水輪機、太 陽能引擎等。可惜這些裝 置都受到環境限制，而且 能量轉化效率尚待提高。 2.核反應堆動力系統： 將鈾或鈈等核燃料透過核 裂變釋放熱能，加熱流體 產生蒸汽，驅動渦輪。可 惜它仍有安全風險，如切 爾諾貝爾和福島也曾發生 輻射洩漏的事故。 星島教室 科學探知 黃潤權 中華基督教會 基慧小學（馬灣） STEAM統籌主任 褚鴻鵬 中華基督教會 基慧小學（馬灣） 科學科老師 日常生活中，我們常常看到許多能自動 運作的機械，你會否好奇它們為甚麼能夠動 起來？其實，這不是魔法或僥倖，而是全賴 無數科學家和工程師在物理學、化學、材料 科學等多個領域的苦心鑽研，才能研發出各 種動力裝置。動力裝置是可將各種能量轉化 為動能的機器，只要得到它們的幫助，無論 是汽車、輪船還是飛機都能活動自如。它的 誕生讓人類達至古人從未企及的高度，堪稱 是科學帶來的奇蹟。 本欄，由教育評議會邀請資深 中小學老師、校長及大學講師撰 稿，旨在為學生提供多元化 的STEAM學習材料，引發學 生探求知識的興趣，將學習融入 生活，培養學生的世界觀、敏銳的觸 覺、積極學習的態度。 作者介紹 圖片來源：網上圖片 由 核 圖片來源：網上圖片 圖片來源：中時新聞網 讀社論學 英文 Recently, a large number of secondary s tudent s developed gast roenter i t is af ter returning from mainland exchange tours, sparking widespread discussion online. Some have been rather populist. While it is not appropriate to view exchange activities with an overly negative attitude, the incidents do highlight potential risks that urgently need to be addressed. The authorities must take this issue seriously, strengthen supervision and tackle shortcomings to ensure all aspects are in order. Young students can thus safely and enjoyably learn about the nation's latest developments and foster a sense of national identity. Understanding nation safely and enjoyably According to avai lable informat ion, more than 60 students from seven secondary schools suffered from food poisoning while participating in exchange tours to Shaoguan and Huangshan. It could be due to consuming contaminated food, transmission through close contact with infected peers or exposure to vomit from affected individuals. Some even suggested that certain students fell ill before dining at local restaurants. Given that food safety issues are a likely cause, the best is to allow relevant experts to investigate and prevent similar incidents in the future. In the past, such exchange tours were not common. However, with the rapid integration of the Greater Bay Area in recent years and SAR policies encouraging youth to understand the country, these exchange tours have become prevalent almost like an emerging industry. According to travel agency informat ion, destinations for these tours included not only Shaoguan and Huangshan but also ci t ies like Shenzhen, Guangzhou, Zhuhai, Foshan, Zhongshan, Huizhou, Heyuan or even as far as northern and northeastern China. The SAR supports these exchange tours to encourage students to explore the mainland and achieve a "return of people's hearts" which is also welcomed by the central government. For certain reasons, some Hongkongers have different preconcept ions about the mainland. The food poisoning incidents have reaffirmed their views, which is unfortunate. That said, considering China's vastness and complex condi t ions, i t is not part icularly surprising that some restaurants may have low hygiene standards. (According to some reports, the Shaoguan eatery involved placed food on the ground with flies hovering over it.) If it is confirmed that the students fell ill after consuming unsanitary food, the issue must be taken seriously. Mainland authorities should order the restaurants involved to rectify their practices immediately and blacklist them if violations persist to protect consumers. As f or Hong Kong , the r e ar e a l so nume rous a r ea s f or improvemen t . The increasing mainland exchange tours not only bring lots of benefits but also problems, which is not unexpected. But the key lies in whether regulatory mechanisms can keep pace. For example, regarding the Huangshan exchange tour, which was organized by an agency commissioned by the Education Bureau (EB), were issues such as food intolerance and suitability considered? Was the reputation of the restaurants checked beforehand? The EB should not take a hands-off approach after commissioning the event. Instead, it must take an active role in coordination, ensuring that every aspect is properly handled. If an incident occurs, it must hold the travel agency or tour organizer accountable. This will increase EB workload and may not be welcome, but student safety is paramount and responsibility not to be shirked. Need for EB active supervision Looking ahead, as Hong Kong continues integrating into the national development agenda, there will be more exchange tours. Mor e i s sue s may t hus be expos ed . We encourage students to visit their motherland to personally experience the history, culture and latest developments while broadening their horizons. Meanwhile, these exchange programmes must be of high quality and safe. The SAR is obliged to oversee and coordinate these efforts, working closely with relevant mainland authorities. In short, students should not encounter unpleasant exper iences in the mainland. Otherwise, meaningful visits will turn into ordeals. 翻譯自3月13日《星島日報》社論 （http://std.stheadline.com/） gastroenteritis (n) —— 腸胃炎 populist (adj) —— 民粹的 shortcoming (n) —— 缺點 foster (v) —— 培養 vomit (n) —— 嘔吐物 prevalent (adj) —— 盛行的 preconception (n) —— 偏見 ordeal (n) —— 煎熬 national identity —— 國民身份 food poisoning —— 食物中毒 emerging industry —— 新興產業 hands-off approach —— 不干預態度 The Centre for Health Protection (CHP) said some of the acute gastroenteritis (AGE) cases could be infected by consuming contaminated food and had notified the Guangdong authority of the relevant restaurants. It has also provided health advice to the affected schools on the transmission, prevention and infection control measures. 1. The word _____ in the first paragraph is the opposite of "suppress". 2. Food safety issues should be tackled by relevant _____. 3. In the passage, the word _____ means "systems". 4. There will be more mainland _____ tours in the future. 5. According to the last paragraph, unpleasant experiences in the mainland will turn meaningful visits into _____. Answers 1. foster 2. experts 3. mechanisms 4. exchange / study 5. ordeals & Q A Vocabulary Useful Terms Did you know? Don't let study tours turn sour, check food hygiene 翻譯︰George D6 侷芎 06.11.2025 星期三
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