第三讲 科学小实验
教学目标：1、掌握科学小实验的制作方法及相关知识和原理；
2、讲授时条理清晰，语言规范，逻辑性强，通俗易懂，实验操作规范。
教学重点：掌握科学小实验的相关知识和原理，授课时的科学性和艺术性。 教学难点：科学小实验原理的迁移和创新意识。 教学方法：讲解法 教学课时：12课时 教学过程： 要求：
1、每班分6个小组；
2、每一个小组二节课，每个小组成员都要上台讲授（或录像） 3、学生和教师共同点评和评分
4、内容可以选下面70个物理科学小实验中的一个，也可以自行选取其它小实验
70个物理科学小实验
实验1 能自己跳开的纸杯 ····························································································· 实验2 吹不出来——神奇的兵乓球 ·················································································· 实验3 试管自动上升 ···································································································· 实验4 大力士——纸 ···································································································· 实验5 不同的承载量 ··································································································· 实验6 测量浮力 ·········································································································· 实验7 会听话的小瓶（简易浮沉子） ··············································································· 实验8 冰块融化后会怎样 ····························································································· 实验9 自动旋转的奥秘 ································································································ 实验10 小船与船浆 ······································································································ 实验11 水的压力 ········································································································· 实验12 帕斯卡桶裂 ······································································································ 实验13 笔帽潜水员 ····································································································· 实验14 冲不走的乒乓球································································································ 实验15 水中悬蛋 ········································································································ 实验16 火山爆发 ········································································································ 实验17 水球的泳姿 ····································································································· 实验18 空气有重量吗？································································································ 实验19 用声音?吹灭?蜡烛······························································································ 实验20 有孔纸片托水 ··································································································· 实验21 手绢的秘密 ······································································································ 实验22 掉不下去的塑料垫板 ························································································· 实验23 蜡烛吹不灭 ······································································································ 实验24 蜡烛抽水机 ······································································································ 实验25 瓶内吹气球 ····································································································· 实验26 能抓住气球的杯子 ···························································································· 实验27 会吸水的杯子 ·································································································· 实验28 会吃鸡蛋的瓶子································································································
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实验29 瓶子瘪了 ········································································································· 实验30 会跳远的乒乓球 ······························································································· 实验31 会吹泡泡的瓶子································································································ 实验32 这样扎气球,气球会爆炸吗？ ················································································ 实验33 瓶子赛跑 ········································································································ 实验34 烧不坏的手绢 ·································································································· 实验35 冷水也能沸腾 ·································································································· 实验36 可爱的浮水印 ·································································································· 实验37 分合的水流 ····································································································· 实验38 漂浮的针 ········································································································ 实验39 神奇的牙签 ····································································································· 实验40 自己会走路的杯子 ···························································································· 实验41 纸杯旋转灯 ······································································································ 实验42 飞行的塑料袋 ··································································································· 实验43 云的形成 ········································································································· 实验44 烧不断的棉线 ··································································································· 实验45 糖的燃烧 ········································································································· 实验46 变色的碘 ········································································································ 实验47 神奇墨水 ······································································································· 实验48 烛火熄灭了 ······································································································ 实验49 空中点烛 ········································································································ 实验50 食盐黏结剂 ····································································································· 实验51 光与彩虹（人造彩虹） ······················································································ 实验52 人造彩虹 ········································································································· 实验53 纽扣的出现与消失 ···························································································· 实验54 水制放大镜 ····································································································· 实验55 没有胶水，报纸也能贴在墙上 ············································································· 实验56 间歇趣泉 ········································································································· 实验57 米粒四射——电荷性质的魅力 ············································································· 实验58 胡椒粉与盐巴的分离 ························································································· 实验59 火焰开关 ········································································································· 实验60 带电的气球 ······································································································ 实验61 感受高压电 ····································································································· 实验62 汤匙变磁铁 ····································································································· 实验63 会上滚的圆锥 ··································································································· 实验64 吹气断铁丝 ······································································································ 实验65 幻杯 ·············································································································· 实验66 电动硬币 ········································································································ 实验67简易电动机 ······································································································ 实验68隔杯转星 ········································································································· 实验69自制水果电池 ··································································································· 实验70 喷泉 ···············································································································
实验1 能自己跳开的纸杯
准备材料：两只纸杯（或轻的塑料杯）
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实验步骤：
1．把两只纸杯重叠好后，搁在桌面上；
2．用手轻轻抓住下面的纸杯，用力对上面的纸杯沿水平方向吹气，上面的纸杯便会迅速地 跳离开来。 实践几分钟后，教师可组织学生比赛，看谁的纸杯先跳起来。
实验中的科学： 当我们对上面的纸杯沿水平方向吹气时，纸杯上面的空气流动速度加快，气压减小，而纸杯下面的空气流动速度没有改变，气压也没有改变，这样，由于纸杯下面气压较大，就把纸杯压上去了，你也不妨试试！
这一现象是荷兰物理学家伯努利首先发现的，也就是伯努利原理。丹尼尔·伯努利在1726年首先提出的原理的内容是：在水流或气流里，如果速度小，压力就大，如果速度大，压力就小。丹尼尔·伯努利(Bernoulli，Daniel)，1700年2月8日生于荷兰格罗宁根，1782年3月17日卒于瑞士巴塞尔，是伟大的数学家、物理学家、医学家。
你知道吗？鸟儿、飞机等也就是这样升上天的！
实验2 吹不出来——神奇的兵乓球 实验准备：
乒乓球一个、漏斗一个 实验步骤：
拿一个乒乓球放在漏斗里，仰着头，往漏斗里吹气，比一比，看谁能把乒乓球从漏斗中吹出来?
2．同学们说：这还不容易吗? 老师说：容易？大家试试。
3．事实告诉我们：越是使劲想把乒乓球吹出来，它越是呆在那里不动。
实验中的科学： 这是因为当气流从漏斗中吹出来时，冲击乒乓球的表面，气流绕着乒乓球往上涌，这时乒乓球下部的压力比大气的压力小，因而使乒乓球无法跳出漏斗。你越是使劲吹，乒乓球下面的气流速度越快，压力也越低，大气的压力就会把球死死地“摁”在漏斗里。
实验3 试管自动上升
思考: 你能让试管自动向上走动吗?自己亲自做做看。 实验准备：
粗细试管各1支（要求粗管的内径稍大于细管外径，然后倒置，细试管将向下落）、水
实验操作：
1.先做无水的情况下，将细试管插入粗试管中，然后倒置，细试管将向下落；
2.在粗试管中盛适量的水，把细试管插入一小段，然后倒置。让水由两管之间的间隙中流
下。细试管在水流下落的过程中会自动的上升。
实验中的科学: 粗试管中无水时，细试管由于受到重力作用，就会下落。而粗试管中有水时，细试管上方是水，下方是空气，细试管会在大气压力的作用下，向上运动。地球对周围物体的压力叫做大气压力。随着距离地面高度变化，大气压力也在变化，位置越高，压力越小；位置越低，压力越小。 创造：你还能用什么实验证明大气压力的存在，并感受到大气压力很大。
实验4 大力士——纸
思考：你能想象一张纸能够举起一本书？你知道怎样才能做到吗？ 实验准备：纸、胶带、1本书 实验操作：
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把纸放在两本并排分开放的书上，使纸的中间部分悬空。 把一本书放在纸的悬空处，纸张很快就会弯曲。 2. 把纸卷成一个纸卷，用胶带粘好纸的边缘处。
3. 把纸卷立起来，并在上面放一本书，甚至放更多的书，纸张都不会变形。 4. 思考两种方法的不同之处。 实验中的科学：
1. 一张纸能承受多大的压力，主要取决于纸张受力时的弯矩。弯矩即纸张的受力点和受反作用力的点之间的距离。弯矩越大，纸张承受的力越大，反之越小。
2. 直接把重物放在纸上，则纸的受力点和受反作用力点几乎在同一位置上。因此弯矩小，所承受的力就小。
3. 把重物放在竖直的纸卷上，纸的弯矩较大，因此承 受的力较多。 创造：想一想，把纸还可以折成哪些形状，以便承担压力。
实验5 不同的承载量
思考：为什么卡纸变形后，它的承载量会不同 ？ 实验准备：纸卡1张(30×20cm)、相同高的纸盒两个、硬币若干枚 实验操作：
一张卡纸悬空平放在相同高度的纸盒上， 纸上只能放两枚硬币。
2. 把纸卡折成波浪形状，架在相同高的纸盒上，波浪形状的卡纸上能放多枚硬币。 实验中的科学： 波浪的卡纸比平整的卡纸弯距大，其承受的力也就较大。 创造： 怎样变化卡纸，使卡纸上放的硬币更多？
实验6 测量浮力
思考:当我们躺在水面上像帆船一样漂浮着,我们都知道是水的浮力在支撑我们。但你可知道怎样测量浮力吗？
实验准备：1个弹簧秤、1把锁、1个装水的玻璃杯 实验操作：
1. 先把锁挂在弹簧秤下，记录弹簧秤的刻度；
2. 然后将弹簧秤下挂的锁放入水中，记录此时弹簧秤的刻度； 3. 比较两次记录下的刻度，思考为什么会不同。 实验中的科学：
1. 锁浸在水中，会受到水对它的向上的支持力，即浮力。 2. 两次记录的差值就是水对铜锁的浮力。
创造： 用弹簧秤再称别的物体（比如小铁块，橡皮头等），观察不同的物体的浮力大小。
实验7 会听话的小瓶（简易浮沉子）
思考：你在电影或电视剧中看到过潜水艇吗？知道潜水艇为什么能浮于水面，又能潜入水中， 它是怎么实现向上浮和向下潜的呢？
实验准备：废旧塑料饮料瓶（500-1000ml，透明有盖）、口服液小瓶、注射器等。 实验操作：
1．在饮料瓶中装入一定量的水，用注射器给口服液小瓶中压入适量的水，使之放入水中时只能有少部分露出水面；
2．把口服液小瓶放入饮料瓶中，然后盖紧瓶盖（如下中图），尽量做到不漏气；
3．用力挤压饮料瓶，可看到口服液小瓶下沉(如下右图)。撤去压力，可看到口服液小瓶向上浮起。用
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力得当，可使口服液小瓶停止在水中某一位置。 注意瓶中水尽量装得满一些， 残留的气体越少，实验效果越好。
实验中的科学： 小瓶放入水中由于所受浮力等于重力，
所以会浮于水面。当用力挤压饮料瓶时，瓶内气压增大，会有一部分水被压入口服液小瓶，使口服液小瓶重力变大，重力大于浮力，小瓶就会下沉。撤去压力时，瓶内气压变小，会有一部分水被流出口服液小瓶，使口服液小瓶重力变小，重力小于浮力，小瓶就会上浮了。用力得当，会使口服液小瓶中的水适当，重力等于浮力，小瓶就会停止在水中某一位置了。潜水艇就是这样实现向上浮和向下潜的。（如果想看到口服液小瓶中水的变化，可以在小瓶中用注射器装入有颜色的水） 附：潜水艇的原理及自制潜水艇模型
靠改变潜艇的自身重量来实现的。潜艇它有多个蓄水仓。当潜艇要下潜时就往蓄水舱中注水，使潜艇重量增加超过它的排水量，潜艇就下潜。
物体在液体中的下沉、上浮两个动态过程中的受力分析。大家都知道潜水艇是一种军用舰艇，它可以潜人水下航行，进行侦察和袭击。但是对潜水艇的工作原理，许多同学则说不清楚，甚至有人误认为：潜水艇浸没水面后就下沉；直至沉底。其实潜水艇淹没水中后，排开水的体积不再变化，它所受到的浮力就不变了，控制它的下潜深度是靠改变水舱的水量(即改变重力)来实现的。当水舱里的水量保持不变时，潜水艇在水下某一深处是处于悬浮状态而不是沉底。
补充：悬浮就是让浮力=重力就好。水仓进水这是最初的潜水艇，当然潜入的水深较浅。现在应该已经没有这种骨灰级的潜艇了。外加动力是现在潜艇是现在潜艇潜水的主要方法。人们根据沉浮原理成功地制造了潜水艇，这种能在水下作战的舰艇在历次海战中都显示其战斗力，它能下潜离水面深达500米，具有良好的隐蔽性和续航力，能从水下袭击水面舰船和岸上目标，也能作侦察、布雷和运输等。
实验8 冰块融化后会怎样
思考：在一个杯子中放一个冰块，然后倒满水。当冰融化后，杯内的水会溢出来吗？ 实验准备： 1块冰块、2个杯子、水 实验操作：
1.在桌面上放置一个空杯子，在空杯子中放入一块冰； 2.往杯中倒满水，会看到冰块的一大部分会高出水面； 3.等待冰块融化，观察融化后，水会不会溢出杯子。 实验中的科学：
水结冰时体积会增大九分之一，因此与同体积的水比较，质量变轻，自然会浮在水面上。当冰块融化时，它失去的是增加的那九分之一的体积，因此，水不会溢出。 其实冰块在水面以下的那部分，就是整个冰块熔化成的水的体积。
想一想：你能用学过的浮力知识对这一问题做出进一步的解释吗？
实验9 自动旋转的奥秘
思考：装满水的纸盒为什么会转动？
实验准备：空的牛奶纸盒、钉子、60厘米长的绳子、水槽、水 实验操作：
1.用钉子在空牛奶盒上扎五个孔 ；
2.一个孔在纸盒顶部的中间，另外四个孔在纸盒四个侧面的左下角 ； 3.将一根大约60厘米长的绳子系在顶部的孔上 ；
4.将纸盒放在盘子上，打开纸盒口，快速地将纸盒灌满水； 5.用手提起纸盒顶部的绳子，纸盒顺时针旋转 。
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