微观ch04
CH04-3.4.5.6保守力与非保守力势能
保守力势能的计算
计算方法
根据保守力势能的定义，通过积分计算势能值。
常见保守力势能
重力势能、弹性势能、电势能等。
保守力势能的应用
物理现象
保守力势能是自然界中广泛存在 的现象，如重力势能、弹性势能
等。
工程应用
在机械、建筑、航空航天等领域， 保守力势能的应用十分广泛，如桥 梁、高层建筑、航天器轨道设计等。
交通工具
保守力势能在交通工具方面有应用，如汽车、 火车等利用燃料燃烧产生的能量转化为动能 和势能；非保守力势能在交通工具方面也有 应用，如飞机利用空气阻力和升力进行飞行。
05 总结与展望
总结
保守力与非保守力势能是物理学中非常重要的概 念，它们在描述和解释自然现象中起着至关重要 的作用。
非保守力势能则主要涉及摩擦力、粘滞力和热传 导等，这些力对应的势能形式与保守力势能有所 不同，如与路径有关、不具有势能零点等。
科学研究
保守力势能在物理学、天文学、地 球科学等领域的研究中具有重要意 义，如万有引力定律、弹性力学等 理论的建立和发展。
02 非保守力势能
非保守力势能的定义与特性
定义
非保守力势能是由于非保守力引起的 势能。非保守力是指力的大小和方向 与物体运动路径有关，而不是只与物 体位置有关的力。
特性
非保守力势能的大小和方向会随着物 体运动路径的变化而变化，因此它不 是由物体的位置决定的，而是由物体 的运动状态决定的。
意义
非保守力势能的研究对于理解物体的运动规律、能量转化和传递以及工程应用等 方面都具有重要意义。
03 保守力与非保守力的比较
特性比较
保守力
在运动过程中，保守力做的功与路径无关，只与初末位置有关，即保守力沿任意路径所做的功等于零 。
微观经济学.ch04.生产理论
2.固定投入比例的生产函数
固定投入比例的生产函数：表示在每一个产量水平上任何一对要 素投入量的比例都是固定不变的。用函数式表示： Q=min(
一、一种可变生产要素的生产函数
Q=f（L, K ）
我们现在来考察一下，当资本固定不变，而劳动投入可变的情 况下，厂商如何通过增加劳动投入来提高产量。
二、总产量、平均产量和边际产量
总产量：使用一定量的某种要素投入所获得的产量总和。即 TPL=Q=f(L)=APL•L 平均产量：平均每单位变动要素投入所能生产的产量。即 APL=TPL/L= f(L)/L 边际产量：每增加一单位变动要素投入所增加的总产量。即 MPL=TPL/L或MPL = dTPL/dL
MPL MPK 即: w r MPK r
MPL w
5. 生产要素的最优组合
2)既定产量条件下成本最小化
MPL MPK 即:
w r MPK r
MPL w5. Leabharlann 产要素的最优组合当 MP w
L
MP r
K
时，说明一单位成本的 支出，用
来购买劳动所得的边际 产量大于用来购买资本 获得的边际产量，因此 ，厂商会扩大劳动投入 量，减少资本投入量， 直到 MP w
例如：农业生产中劳动量、水 或者肥料等要素的投入。 原因：任何一种产品的生产技 术都要求各个要素投入之间有 适当的比例，这意味着要素之 间的替代是有限制的。
K
5 4 3
2
原子物理与量子力学
原子物理与量子力学Atomic Physics and Quantum Mechanics哈尔滨理工大学应用科学学院应用物理系相关说明一、课程名称原子物理与量子力学二、计划学时108（每周3次6学时）三、课程性质技术基础课四、适用专业应用物理学、材料物理学、光信息科学与技术、电子科学与技术五、主要内容本课程内容主要可分为两大部分：1、原子物理学；2、量子力学。
原子物理学主要介绍原子物理学的发展。
从光谱学、X射线等方面的实验事实总结出能级规律，进一步分析原子结构的特点。
量子力学是二十世纪初建立起来的一门崭新的学科。
通过五个基本原理的引入，逐步构筑了量子力学的理论框架。
教学过程中，尽可能将两部分的相关内容结合讲授，利于学生理解和吸收。
原子物理学与量子力学是物理类学生的理论基础。
通过该课程的学习，学生应掌握有关原子等微观粒子的基本物理概念及反映其物理性质的基本规律，使学生了解和掌握现代一些重要的物理观念，并为应用技术准备理论基础。
六、教材与参考书《原子物理学》，褚圣麟，高教出版社《量子力学教程》，周世勋，高教出版社七、备注本课程采用多媒体教学，重点难点等采用特定的文字表现方式或动画声音等形式体现，可在“《原子物理与量子力学》课件”的相关章节观察效果。
目录绪论 (1)本章小结 (1)第一章原子的基本状况 (2)§1.1 原子的质量和大小 (2)§1.2 原子的核式结构 (2)本章小结 (3)第二章原子的能级和辐射 (4)§2.1 原子光谱的一般情况与氢原子光谱 (4)§2.2 经典理论的困难和光的波粒二象性 (4)§2.3 玻尔氢原子理论 (5)§2.4 类氢体系光谱 (5)§2.5 夫兰克-赫兹实验 (5)§2.6 量子化通则 (6)§2.7 电子的椭圆轨道 (6)§2.8 史特恩-盖拉赫实验与原子空间取向的量子化 (7)§2.9 量子理论与经典理论的对应关系对应原理 (7)本章小结 (7)第三章量子力学的运动方程—Schrödinger方程 (8)§3.1 物质的波粒二象性 (8)§3.2 波函数的统计解释 (8)§3.3 态叠加原理 (9)§3.4 薛定谔方程 (9)§3.5 几率守恒定律与定态薛定谔方程 (9)§3.6 一维无限深势阱 (10)§3.7 势垒贯穿 (10)§3.8 线性谐振子 (10)§3.9 电子在库仑场中的运动 (11)§3.10 氢原子 (11)本章小结 (12)第四章量子力学中的力学量 (13)§4.1 力学量算符 (13)§4.2 动量算符与角动量算符 (13)§4.3 厄密算符的本征函数 (14)§4.4 力学量的取值分布 (14)§4.5 算符的对易关系 (14)§4.6 测不准关系 (15)§4.7 守恒定律 (15)本章小结 (16)第五章碱金属原子的光谱和能级 (17)§5.1 碱金属原子的光谱和结构特点 (17)§5.2 碱金属原子光谱的精细结构 (17)§5.3 电子自旋与轨道运动的相互作用 (18)§5.4 单电子跃迁的选择定则 (18)*§5.5 氢原子光谱的精细结构与蓝姆移动 (18)本章小结 (19)第六章多电子原子 (20)§6.1 氦与第二族元素的光谱和能级 (20)§6.2 具有两个价电子的原子态 (20)§6.3 泡利原理与同科电子 (21)§6.4 复杂原子光谱的一般规律 (21)§6.5 辐射跃迁的普适选择定则 (21)§6.6 He-Ne激光器 (22)本章小结 (22)第七章磁场中的原子 (23)§7.1 原子的磁矩 (23)§7.2 外磁场对原子的作用 (23)§7.3 史特恩-盖拉赫实验的结果 (23)§7.4 顺磁共振 (24)*§7.5 物质的磁性 (24)§7.6 塞曼效应 (25)本章小结 (25)第八章原子的壳层结构 (26)§8.1 元素性质的周期性 (26)§8.2 原子的电子壳层结构 (26)§8.3 原子基态的电子组态 (26)本章小结 (27)第九章X射线 (28)§9.1 X射线的产生及测量 (28)§9.2 X射线的发射谱及相关能级 (28)*§9.3 X射线的吸收和散射 (28)*§9.4 X射线在晶体中的衍射 (29)本章小结 (29)第十章态和力学量的表象 (30)§10.1 态的表象 (30)§10.2 算符的矩阵表示 (30)§10.3 量子力学公式的矩阵表述 (31)§10.4 幺正变换 (31)§10.5 狄拉克符号 (31)§10.6 占有数表象 (32)本章小结 (32)第十一章微扰理论 (33)§11.1 非简并定态微扰理论及其应用 (33)§11.2 简并情况下的微扰理论及其应用 (33)§11.3 变分法与氦原子基态 (34)§11.4 与时间有关的微扰理论 (34)§11.5 跃迁几率 (34)§11.6 光的发射与吸收 (35)*§11.7 选择定则 (35)本章小结 (36)第十二章散射 (37)§12.1 碰撞过程与散射截面 (37)§12.2 中心力场中的弹性散射（分波法） (37)本章小结 (37)第十三章自旋与全同粒子 (39)§13.1 电子的自旋 (39)§13.2 电子自旋的描述 (39)§13.3 简单塞曼效应 (40)§13.4 角动量的耦合及应用 (40)§13.5 光谱的精细结构 (41)§13.6 全同粒子体系 (41)§13.7 全同粒子体系的波函数 (41)§13.8 两个电子的自旋函数 (42)本章小结 (42)绪论绪论本章主要介绍原子物理与量子力学的发展过程，并指出学习新理论应注意的问题。
张凯：【体育科学研究方法】CH04选题规划
和对未来研究的提示和建议；
对文献敢于质疑：
他们为什么要做这些？ 这个结果与我自己在生活中看到的一致吗？ 这个预测如何应用到不同的领域中去？
36
聚焦、聚焦、再聚焦
一次阅读会引发很多研究设想，但一个研究中不
可能解决所有问题；
必须放弃大部分想法； 在一个时间内，要放弃无关的项目，聚焦在一个
2
北京体育大学2006届优秀学士论文
北京市海淀区中学生压力源、压力应对方式及其与体育锻炼的关系 拓展训练场地高空项目安全保障方法研究 对我国优秀女子铁饼运动员王钰投掷技术的三维运动学分析 北京高校大学生志愿者满意度研究 高低杠反吊大回环转体720度成扭臂的技术分析和教法研究 对中国电子竞技“魔兽争霸3”发展的研究 北京体育大学教育学院学生选散打作为专项动机的调查与分析
缺少坚实的理论基础 缺少严格的科研方法训练
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提倡实证研究
经验是知识的惟一来源：伽利略的实验 实证主义哲学观的思维逻辑 “实证研究应当成为基本范式吗”是否
落后于时代精神？
19
实证主义社会科学
目标是发现和记录人类行为的普遍法则； 精确的定量资料，使用实验法、调查法、统计分
43
本科学士论文题目：
实证研究明确界定自变量、因变量
有氧运动对ApoE基因缺陷小鼠高密度脂蛋白受体SR— BI基因表达的影响； 刺五加制剂对中老年人恒定负荷运动中脂肪利用的影响 成人生命周期中人格的年龄变异：五种不同文化的比较
多余界定
浅谈….. 试论….. …..的研究
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在生活、学习实践中发现问题
北京体育大学本科生恋爱价值观现状调查研究 北京体育大学社体专业学生对英语学习态度及其干预
ch04 收入效应与替代效应
转动和移动
X2 最初预算线 A D X’2 初始选择 最终选择 最终预算线 移动 转动后的预算线 转动 X’1 B E C X1
纯替代效应
纯替代效应是由相对价格变化而引起的 消费需求的变化 讨论纯替代效应的时候要控制实际收入 变化的影响， 变化的影响，即先将这个消费者的收入 调整， 调整，调整后的收入刚好能够按照新的 价格购买原来的消费组合。 价格购买原来的消费组合。
（用绝对量表示的Slutsky方程） 用绝对量表示的Slutsky方程） Slutsky方程
Slutsky方程的推导 方程的推导
∆p1 = −∆m / x1
将上式代入
∆x1 ∆x1 ∆x1 = + ∆p1 ∆p1 ∆p1
s
s m
n
得出Slutsky方程 ∆x1 = ∆x1 − ∆x1 x 方程 得出 1
中级微观经济学 Intermediate microeconomics
Lecture 4 替代效应与收入效应
替代效应与收入效应
价格效应 Hicks方法 方法 Slutsky方法 方法 几个例子 一般化的Slutsky方程 方程 一般化的
价格效应
一个商品的价格变化对需求带来的影 价格效应（ 响 —— 价格效应（price effect） ） 替代效应（ 替代效应（substitution effect） ） 收入效应（ 收入效应（income effect） ）
替代和收入效 应同方向作用 ，正常商品 替代效应>收入效应 替代效应 收入效应 低档商品 替代效应<收入效应 替代效应 收入效应 吉芬商品
Slutsky方法与正常商品
大多数商品是正常商品， 大多数商品是正常商品，替代效应与收 入效应作用方向一致。 入效应作用方向一致。 正常商品的需求曲线是向下倾斜的 （downward slopping）。 ）。 需求法则： 需求法则：如果一种商品的需求随着收 入的增加而增加， 入的增加而增加，那么这种商品的需求 一定随着价格的上升而下降。 一定随着价格的上升而下降。
微观经济学Ch04
CHAPTER 4 INDIVIDUAL AND MARKET DEMAND1. Explain the difference between each of the following terms:a. a price consumption curve and a demand curve;A price consumption curve identifies the utility maximizing combinations of two goods as the price of one of the goods changes. When the price of one of the goods declines, thebudget line will pivot outwards, and a new utility maximizing bundle will be chosen. Theprice consumption curve connects all such bundles. A demand curve is a graphical relationship between the price of a good and the (utility maximizing) quantity demanded ofa good, all else the same. Price is plotted on the vertical axis and quantity demanded on thehorizontal axis.b. an individual demand curve and a market demand curve;An individual demand curve identifies the (utility maximizing) quantity demanded by oneperson at any given price of the good. A market demand curve is the sum of the individual demand curves for any given product. At any given price, the market demand curveidentifies the quantity demanded by all individuals, all else the same.c. an Engel curve and a demand curve;A demand curve identifies the quantity demanded of a good for any given price, holding income and all else the same. An Engel curve identifies the quantity demanded of a good forany given income, holding prices and all else the same.d. an income effect and a substitution effect;The substitution effect measures the effect of a change in the price of a good on theconsumption of the good, utility held constant. This change in price changes the slope of thebudget line and causes the consumer to rotate along the current indifference curve. The income effect measures the effect of a change in purchasing power (caused by a change inthe price of a good) on the consumption of the good, relative prices held constant. Forexample, an increase in the price of good 1 (on the horizontal axis) will rotate the budget linedown along the indifference curve as the slope of the budget line (the relative price ratio) changes. This is the substitution effect. This new budget line will then shift inwards to reflect the decline in purchasing power caused by the increase in the price of the good. Thisis the income effect.3. Explain whether the following statements are true or false.a. The marginal rate of substitution diminishes as an individual moves downward alongthe demand curve.This is true. The consumer will maximize his utility by choosing the bundle on his budgetline where the price ratio is equal to the MRS. Suppose the consumer chooses the quantity ofgoods 1 and 2 such that P 1P 2MRS . As the price of good 1 falls, the price ratio becomes a smaller number and hence the MRS becomes a smaller number. This means that as the priceof good 1 falls, the consumer is willing to give up fewer units of good 2 in exchange foranother unit of good 1.b. The level of utility increases as an individual moves downward along the demandcurve.This is true. As the price of a good falls, the budget line pivots outwards and the consumer isable to move to a higher indifference curve.c.Engel curves always slope upwards.This is false. The Engel curve identifies the relationship between the quantity demanded of agood and income, all else the same. If the good is inferior, then as income increases, quantitydemanded will decrease, and the Engel curve will slope downwards.5. Which of the following combinations of goods are complements and which are substitutes? Could they be either in different circumstances? Discuss.a. a mathematics class and an economics classIf the math class and the economics class do not conflict in scheduling, then the classes couldbe either complements or substitutes. The math class may illuminate economics, and theeconomics class can motivate mathematics. If the classes conflict, they are substitutes.b. tennis balls and a tennis racketTennis balls and a tennis racket are both needed to play a game of tennis, thus they arecomplements.c. steak and lobsterFoods can both complement and substitute for each other. Steak and lobster can compete, i.e.,be substitutes, when they are listed as separate items on a menu. However, they can alsofunction as complements because they are often served together.d. a plane trip and a train trip to the same destinationTwo modes of transportation between the same two points are substitutes for one another.e. bacon and eggsBacon and eggs are often eaten together and are, therefore, complementary goods. Byconsidering them in relation to something else, such as pancakes, bacon and eggs can functionas substitutes.7. Which of the following events would cause a movement along the demand curve for U.S.-produced clothing, and which would cause a shift in the demand curve?a. the removal of quotas on the importation of foreign clothesThe removal of quotas will shift the demand curve inward for domestically-produced clothes,because foreign-produced goods are substitutes for domestically-produced goods. Both theequilibrium price and quantity will fall as foreign clothes are traded in a free marketenvironment.b. an increase in the income of U.S. citizensWhen income rises, expenditures on normal goods such as clothing increase, causing thedemand curve to shift out. The equilibrium quantity and price will increase.c. a cut in the industry’s costs of producing domestic clothes that is passed on to the market in theform of lower clothing pricesA cut in an industry’s costs will shift the supply curve out. The equilibri um price will fall andquantity will increase. There is a movement along the demand curve.9. Suppose that the average household in a state consumes 800 gallons of gasoline per year. A 20-cent gasoline tax is introduced, coupled with a $160 annual tax rebate per household. Will the household be better or worse off under the new program?If the household does not change its consumption of gasoline, it will be unaffected by the tax-rebate program, because in this case the household pays 0.20*800=$160 in taxes and receives$160 as an annual tax rebate. The two effects would cancel each other out. To the extent thatthe household reduces its gas consumption through substitution, it must be better off. Thenew budget line (price change plus rebate) will pass through the old consumption point of 800gallons of gasoline, and any now affordable bundle that contains less gasoline must be on ahigher indifference curve. The household will not choose any bundle with more gasolinebecause these bundles are all inside the old budget line, and hence are inferior to the bundlewith 800 gallons of gas.11. Explain which of the following items in each pair is more price elastic.a.The demand for a specific brand of toothpaste and the demand for toothpaste in general.The demand for a specific brand is more elastic since the consumer can easily switch toanother brand if the price goes up.b.The demand for gasoline in the short run and the demand for gasoline in the long run.Demand in the long run is more elastic since consumers have had more time to adjust to thechange in price.1. An individual sets aside a certain amount of his income per month to spend on his two hobbies, collecting wine and collecting books. Given the information below, illustrate both the price consumption curve associated with changes in the price of wine, and the demand curve for wine.The price consumption curve connects each of the four optimal bundles given in the tableabove. As the price of wine increases, the budget line will pivot inwards and the optimalbundle will change.4. a. Orange juice and apple juice are known to be perfect substitutes. Draw the appropriate price-consumption (for a variable price of orange juice) and income-consumption curves.We know that the indifference curves for perfect substitutes will be straight lines. In this case,the consumer will always purchase the cheaper of the two goods. If the price of orange juice isless than that of apple juice, the consumer will purchase only orange juice and the priceconsumption curve will be on the “orange juice axis” of the graph (point F). If apple juice ischeaper, the consumer will purchase only apple juice and the price consumption curve will beon the “apple juice axis” (point E). If the two goods have the same price, the consumer will beindifferent between the two; the price consumption curve will coincide with the indifferencecurve (between E and F). See the figure below.Assuming that the price of orange juice is less than the price of apple juice, the consumer willmaximize her utility by consuming only orange juice. As the level of income varies, only theamount of orange juice varies. Thus, the income consumption curve will be the “orange juiceaxis” in the figure below.4.b. Left shoes and right shoes are perfect complements. Draw the appropriate price-consumption and income-consumption curves.For goods that are perfect complements, such as right shoes and left shoes, we know that theindifference curves are L-shaped. The point of utility maximization occurs when the budgetconstraints, L1 and L2 touch the kink of U1 and U2. See the following figure.In the case of perfect complements, the income consumption curve is also a line through thecorners of the L-shaped indifference curves. See the figure below.6. Two individuals, Sam and Barb, derive utility from the hours of leisure (L) they consume and fromthe amount of goods (G) they consume. In order to maximize utility they need to allocate the 24 hours in the day between leisure hours and work hours. Assume that all hours not spent working areleisure hours. The price of a good is equal to $1 and the price of leisure is equal to the hourly wage. We observe the following information about the choices that the two individuals make:Graphically illustrate Sam’s leisure demand curve and Barb’s leisure demand curve. Place price on the vertical axis and leisure on the horizontal axis. Given that they both maximize utility, how can you explain the difference in their leisure demand curves?It is important to remember that less leisure implies more hours spent working at the higher wage. Sam’s leisure demand curve is downward sloping. As the price of leisure (the wage)rises, he chooses to consume less leisure to spend more time working at a higher wage tobuy more goods. Barb’s leisure demand curve is upward sloping. As the price of leisurerises, she chooses to consume more leisure since her working hours are generating more income. This difference in demand can be explained by examining the income andsubstitution effects for the two individuals. The substitution effect measures the effect of thechange in the price of leisure, keeping utility constant (the budget line will rotate around the current indifference curve). Since the substitution effect is always negative, a rise in theprice of leisure will cause both individuals to consume less leisure. The income effectmeasures the change in purchasing power caused by the change in the price of leisure. Here, when the price of leisure (the wage) rises, there is an increase in purchasing power (the newbudget line will shift outwards). Assuming both individuals consider leisure to be a normalgood (this is not a necessary assumption for Sam), then the increase in purchasing powerwill increase demand for leisure. For Sam, the reduction in leisure demand caused by the substitution effect outweighs the increase in demand for leisure caused by the income effect.For Barb, her income effect is larger than her substitution effect.7. The director of a theatre company in a small college town is considering changing the way he prices tickets. He has hired an economic consulting firm to estimate the demand for tickets. The firm has classified people who go the theatre into two groups, and has come up with two demand functions. The demand curves for the general public (Q gp ) and students (Q s ) are given below.Q gp =500-5PQ s =200-4Pa. Graph the two demand curves on one graph, with P on the vertical axis and Q on the horizontal axis. If the current price of tickets is $35, identify the quantity demanded by eachgroup.Both demand curves are downward sloping and linear. For the general public, the vertical intercept is 100 and the horizontal intercept is 500. For the students, the vertical interceptis 50 and the horizontal intercept is 200. The general public demands Q gp =500-5(35)=325tickets and the students demand Q s =200-4(35)=60 tickets.b. Find the price elasticity of demand for each group at the current price and quantity.The elasticity for the general public is εgp=-5(35)325=-0.54 and the elasticity for the students is εgp =-4(35)60=-2.33. If the price of tickets increases by one percent then the general public will demand .54% fewer tickets and the students will demand 2.33% fewertickets.c. Is the director maximizing the revenue he collects from ticket sales by charging $35 for eachticket? Explain.No he is not maximizing revenue since neither one of the calculated elasticities is equal to –1.Since demand by the general public is inelastic at the current price, the director could increase the price and quantity demanded would fall by a smaller amount in percentageterms, causing revenue to increase. Since demand by the students is elastic at the currentprice, the director could decrease the price and quantity demanded would increase by alarger amount in percentage terms, causing revenue to increase.d. What price should he charge each group if he wants to maximize revenue collected from ticketsales?To figure this out, find the formula for elasticity, set it equal to –1, and solve for price and quantity. For the general public:εgp =-5PQ=-15P=Q=500-5PP=50Q=250.For the students:εs =-4PQ=-14P=Q=200-4PP=25Q=100.9. The ACME Corporation determines that at current prices the demand for its computer chips has a price elasticity of -2 in the short run, while the price elasticity for its disk drives is -1.a. If the corporation decides to raise the price of both products by 10 percent, what will happen toits sales? To its sales revenue?We know the formula for the elasticity of demand is:EQP P=%%∆∆.For computer chips, E P = -2, so a 10 percent increase in price will reduce the quantity sold by20 percent. For disk drives, E P = -1, so a 10 percent increase in price will reduce sales by 10percent.Sales revenue is equal to price times quantity sold. Let TR1 = P1Q1 be revenue before the pricechange and TR2 = P2Q2 be revenue after the price change.For computer chips:∆TR cc = P2Q2 - P1Q1∆TR cc= (1.1P1 )(0.8Q1 ) - P1Q1 = -0.12P1Q1, or a 12 percent decline.For disk drives:∆TR dd = P2Q2 - P1Q1∆TR dd = (1.1P1 )(0.9Q1 ) - P1Q1 = -0.01P1Q1, or a 1 percent decline.Therefore, sales revenue from computer chips decreases substantially, -12 percent, while thesales revenue from disk drives is almost unchanged, -1 percent. Note that at the point on thedemand curve where demand is unit elastic, total revenue is maximized.b. Can you tell from the available information which product will generate the most revenue forthe firm? If yes, why? If not, what additional information do you need?No. Although we know the responsiveness of demand to changes in price, we need to knowboth quantities and prices of the products to determine total sales revenue.10. By observing an individual’s behavior in the situations outlined below, determine the relevant income elasticities of demand for each good (i.e., whether the good is normal or inferior). If you cannot determine the income elasticity, what additional information might you need?a. Bill spends all his income on books and coffee. He finds $20 while rummaging through a usedpaperback bin at the bookstore. He immediately buys a new hardcover book of poetry.Books are a normal good since his consumption of books increases with income. Coffee is anormal or neutral good since consumption of coffee did not fall when income increased.b. Bill loses $10 he was going to use to buy a double espresso. He decides to sell his new book at adiscount to his friend and use the money to buy coffee.Coffee is clearly a normal good.c. Being bohemian becomes the latest teen fad. As a result, coffee and book prices rise by 25percent. Bill lowers his consumption of both goods by the same percentage.Books and coffee are both normal goods since his response to a decline in real income is todecrease consumption of both goods.d. Bill drops out of art school and gets an M.B.A. instead. He stops reading books and drinkingcoffee. Now he reads The Wall Street Journal and drinks bottled mineral water.His tastes have changed completely, and we do not know exactly how he would respond toprice and income changes. We need more information regarding his new level of income, andrelative prices of the goods to determine the income elasticities.11. Suppose the income elasticity of demand for food is 0.5, and the price elasticity of demand is –1.0. Suppose also that Felicia spends $10,000 a year on food, the price of food is $2, and her income is $25,000.a.If a sales tax on food were to cause the price of food to increase to $2.50, what wouldhappen to her consumption of food? (Hint: Since a large price change is involved, youshould assume that the price elasticity measures an arc elasticity, rather than a pointelasticity.)The price of food increases from $2 to $2.50, so arc elasticity should be used:.We know that E P = -1, P = 2, ∆P = 0.5, and Q=5000. We also know that Q2, the new quantity, is Thus, if there is no change in income, we may solve for ∆Q:-1=∆Q0.5⎛⎝⎫⎭2+2.525,000+5,000+∆Q()2⎛⎝⎫⎭⎪⎪⎪.By cross-multiplying and rearranging terms, we find that ∆Q = -1,000. This means that she decreases her consumption of food from 5,000 to 4,000 units.b.Suppose that she is given a tax rebate of $2,500 to ease the effect of the sales tax.What would her consumption of food be now?A tax rebate of $2,500 implies an income increase of $2,500. To calculate the response of demand to the tax rebate, use the definition of the arc elasticity of income..We know that E I= 0.5, I = 25,000, ∆I = 2,500, Q = 4,000 (from the answer to 11.a). Assuming no change in price, we solve for ∆Q.0.5=∆Q2,500⎛⎝⎫⎭⎪25,000+27,50024,000+4,000+∆Q()2⎛⎝⎫⎭⎪⎪⎪.By cross-multiplying and rearranging terms, we find that ∆Q= 195 (approximately). This means that she increases her consumption of food from 4,000 to 4,195 units.c.Is she better or worse off when given a rebate equal to the sales tax payments? Draw agraph and explain.Felicia is likely to be better off after the rebate. The amount of the rebate is enough to allow her to purchase her original bundle of food and other goods. Recall that originally she consumed 5000 units of food. When the price went up by fifty cents per unit, she needed an extra 5000*$0.50=$2,500 to afford the same quantity of food without reducing the quantity of the other goods consumed. This is the exact amount of the rebate. However, she did not choose to return to her original bundle. We can therefore infer that she found a better bundle that gave her a higher level of utility. In the graph below, when the price of food increases, the budget line will pivot inwards. When the rebate is given, this new budget line will shift outwards. The bundle after the rebate is on that part of the new budget line that was previously unaffordable, and that lies above the original indifference curve.13. Suppose you are in charge of a toll bridge that costs essentially nothing to operate. The demand for bridge crossings Q is given by P =15-12Q . a. Draw the demand curve for bridge crossings. The demand curve is linear and downward sloping. The vertical intercept is 15 and thehorizontal intercept is 30.b.How many people would cross the bridge if there were no toll? At a price of zero, the quantity demanded would be 30. c. What is the loss of consumer surplus associated with a bridge toll of $5?If the toll is $5 then the quantity demanded is 20. The lost consumer surplus is the area below the price line of $5 and to the left of the demand curve. The lost consumer surplus canbe calculated as (5*20)+0.5(5*10)=$125.d. The toll bridge operator is considering an increase in the toll to $7. At this new higher price, how many people would cross the bridge? Would the toll bridge revenueincrease or decrease? What does your answer tell you about the elasticity of demand?At a toll of $7, the quantity demanded would be 16. The initial toll revenue was $5*20=$100.The new toll revenue is $7*16=$112. Since the revenue went up when the toll was increased, demand is inelastic (the increase in price (40%) outweighed the decline in quantitydemanded (20%)).e. Find the lost consumer surplus associated with the increase in the price of the tollfrom $5 to $7.The lost consumer surplus is (7-5)*16+0.5(7-5)(20-16)=$36.。
曼昆微观经济学答案ch04
The Market Forces of Supply and DemandWHAT’S NEW IN THE THIRD EDITION:This chapter has been completely rearranged and rewritten.LEARNING OBJECTIVES:By the end of this chapter, students should understand:what a competitive market is.what determines the demand for a good in a competitive market.what determines the supply of a good in a competitive market.how supply and demand together set the price of a good and the quantity sold.the key role of prices in allocating scarce resources in market economies.CONTEXT AND PURPOSE:Chapter 4 is the first chapter in a three-chapter sequence that deals with supply and demand and how markets work. Chapter 4 shows how supply and demand for a good determines both the quantityproduced and the price at which the good sells. Chapter 5 will add precision to the discussion of supply and demand by addressing the concept of elasticity —the sensitivity of the quantity supplied and quantity demanded to changes in economic variables. Chapter 6 will address the impact of government policies on prices and quantities in markets.The purpose of Chapter 4 is to establish the model of supply and demand. The model of supply and demand is the foundation for the discussion for the remainder of this text. For this reason, time spent studying the concepts in this chapter will return benefits to your students throughout their study of economics. Many instructors would argue that this chapter is the most important chapter in the text.THE MARKET FORCES OF SUPPLY AND DEMAND52 Chapter 4/The Market Forces of Supply and DemandKEY POINTS:1.Economists use the model of supply and demand to analyze competitive markets. In a competitivemarket, there are many buyers and sellers, each of whom has little or no influence on the market price.2.The demand curve shows how the quantity of a good demanded depends on the price. According tothe law of demand, as the price of a good falls, the quantity demanded rises. Therefore, the demand curve slopes downward.3.In addition to price, other determinants of how much consumers want to buy include income, theprices of substitutes and complements, tastes, expectations, and the number of buyers. If one of these factors changes, the demand curve shifts.4.The supply curve shows how the quantity of a good supplied depends on the price. According to thelaw of supply, as the price of a good rises, the quantity supplied rises. Therefore, the supply curve slopes upward.5.In addition to price, other determinants of how much producers want to sell include input prices,technology, expectations, and the number of sellers. If one of these factors changes, the supply curve shifts.6.The intersection of the supply and demand curves determines the market equilibrium. At theequilibrium price, the quantity demanded equals the quantity supplied.7.The behavior of buyers and sellers naturally drives markets toward their equilibrium. When themarket price is above the equilibrium price, there is a surplus of the good, which causes the market price to fall. When the market price is below the equilibrium price, there is a shortage, which causes the market price to rise.8.To analyze how any event influences a market, we use the supply-and-demand diagram to examinehow the event affects equilibrium price and quantity. To do this we follow three steps. First, we decide whether the event shifts the supply curve or the demand curve (or both). Second, we decide which direction the curve shifts. Third, we compare the new equilibrium with the initial equilibrium.9.In market economies, prices are the signals that guide economic decisions and thereby allocatescarce resources. For every good in the economy, the price ensures that supply and demand are in balance. The equilibrium price then determines how much of the good buyers choose to purchase and how much sellers choose to produce.CHAPTER OUTLINE:I. Markets and CompetitionChapter 4/The Market Forces of Supply and Demand 53A. Definition of market: a group of buyers and sellers of a particular good orservice.B. Definition of competitive market: a market in which there are many buyers andmany sellers so that each has a negligible impact on the market price.C. Competition: Perfect and Otherwise1. Characteristics of a perfectly competitive market:a. The goods being offered for sale are all the same.b. The buyers and sellers are so numerous that none can influence themarket price.2. Because buyers and sellers must accept the market price as given, they are oftencalled "price takers."3. Not all goods are sold in a perfectly competitive market.a. A market with only one seller is called a monopoly market.b. A market with only a few sellers is called an oligopoly.c. A market with a large number of sellers, each selling a product that isslightly different from its competitors‘ products, is called monopolisticcompetition.D. We will start by studying perfect competition.II. DemandA. The Demand Curve: The Relationship between Price and Quantity Demanded1. Definition of quantity demanded: the amount of a good that buyers arewilling and able to purchase.2. One important determinant of quantity demanded is the price of the product.a. Quantity demanded is negatively related to price. This implies that thedemand curve is downward sloping.b. Definition of law of demand: the claim that, other things equal,the quantity demanded of a good falls when the price of thegood rises.54 Chapter 4/The Market Forces of Supply and Demand3. Definition of demand schedule: a table that shows the relationshipbetween the price of a good and the quantity demanded.4. Definition of demand curve: a graph of the relationship between theprice of a good and the quantity demanded. a. Price is generally drawn on the vertical axis.b.Quantity demanded is represented on the horizontal axis.Chapter 4/The Market Forces of Supply and Demand 55B. Market Demand Versus Individual Demand1.The market demand is the sum of all of the individual demands for a particular good or service.2.The demand curves are summed horizontally —meaning that the quantities demanded are added up for each level of price.3.The market demand curve shows how the total quantity demanded of a good varies with the price of the good, holding constant all other factors that affect how much consumers want to buy.C.Shifts in the Demand Curve1. The demand curve shows how much consumers want to buy at any price,holding constant the many other factors that influence buying decisions.2. If any of these other factors change, the demand curve will shift.a. An increase in demand can be represented by a shift of the demandcurve to the right.b.A decrease in demand can be represented by a shift of the demand curve to the left.3.Income56 Chapter 4/The Market Forces of Supply and Demanda.The relationship between income and quantity demanded depends on what type of good the product is.b.Definition of normal good: a good for which, other things equal, an increase in income leads to an increase in demand.c.Definition of inferior good: a good for which, other things equal, an increase in income leads to a decrease in demand.4. Prices of Related Goodsa.Definition of substitutes: two goods for which an increase in theprice of one good leads to an increase in the demand for the other.b.Definition of complements: two goods for which an increase in the price of one good leads to a decrease in the demand for the other.5. Tastes6.Expectationsa. Future Incomeb.Future Prices7. Number of BuyersD.Case Study: Two Ways to Reduce the Quantity of Smoking Demanded1.Public service announcements, mandatory health warnings on cigarette packages, and the prohibition of cigarette advertising on television are policies designed to reduce the demand for cigarettes (and shift the demand curve to the left). 2.Raising the price of cigarettes (through tobacco taxes) lowers the quantity of cigarettes demanded.Chapter 4/The Market Forces of Supply and Demand 57a. The demand curve does not shift in this case, however.b. An increase in the price of cigarettes can be shown by a movementalong the original demand curve.3. Studies have shown that a 10% increase in the price of cigarettes causes a 4%reduction in the quantity of cigarettes demanded. For teens a 10% increase inprice leads to a 12% drop in quantity demanded.4. Studies have also shown that a decrease in the price of cigarettes is associatedwith greater use of marijuana. Thus, it appears that tobacco and marijuana arecomplements.III. SupplyA. The Supply Curve: The Relationship between Price and Quantity Supplied1. Definition of quantity supplied: the amount of a good that sellers arewilling and able to sell.a. Quantity supplied is positively related to price.b. Definition of law of supply: the claim that, other things equal, thequantity supplied of a good rises when the price of the goodrises.2. Definition of supply schedule: a table that shows the relationshipbetween the price of a good and the quantity supplied.3. Definition of supply curve: a graph of the relationship between the priceof a good and the quantity supplied.58 Chapter 4/The Market Forces of Supply and DemandB.Market Supply Versus Individual Supply1. The market supply curve can be found by summing individual supply curves.2. Individual supply curves are summed horizontally at every price.3.The market supply curve shows how the total quantity supplied varies as the price of the good varies.Chapter 4/The Market Forces of Supply and Demand 59C. Shifts in the Supply Curve1. The supply curve shows how much producers offer for sale at any given price, holding constant all other factors that may influence producers‘ decisions about how much to sell.2. When any of these other factors change, the supply curve will shift.a. An increase in supply can be represented by a shift of the supply curve to the right.b.A decrease in supply can be represented by a shift of the supply curve to the left.3. Input Prices4.Technology5. Expectations6. Number of SellersIV. Supply and Demand Together A.Equilibrium 1. The point where the supply and demand curves intersect is called the market‘s equilibrium.2.Definition of equilibrium: a situation in which the price has reached the level where quantity supplied equals quantity demanded.60 Chapter 4/The Market Forces of Supply and DemandDefinition of equilibrium price: the price that balances quantity supplied and quantity demanded.4.The equilibrium price is often called the "market-clearing" price because both buyers and sellers are satisfied at this price.5.Definition of equilibrium quantity: the quantity supplied and the quantity demanded at the equilibrium price.6. If the actual market price is higher than the equilibrium price, there will be asurplus of the good.a. Definition of surplus: a situation in which quantity supplied isgreater than quantity demanded.b.To eliminate the surplus, producers will lower the price until the marketreaches equilibrium.7. If the actual price is lower than the equilibrium price, there will be a shortage ofthe good.a. Definition of shortage: a situation in which quantity demanded isgreater than quantity supplied.b.Sellers will respond to the shortage by raising the price of the good untilthe market reaches equilibrium. Array8. Definition of the law of supply and demand: the claim that the price ofany good adjusts to bring the supply and demand for that good intobalance.B.Three Steps to Analyzing Changes in Equilibrium1. Decide whether the event shifts the supply or demand curve (or perhaps both).2. Decide in which direction the curve shifts.3.Use the supply-and-demand diagram to see how the shift changes the equilibrium price and quantity.A.Example: A Change in Demand — the effect of hot weather on the market for ice cream.ALTERNATIVE CLASSROOM EXAMPLE:Go through these examples of events that would shift either the demand or supply of #2 lead pencils:▪ an increase in the income of consumers▪ an increase in the use of standardized exams (using opscan forms) ▪ a decrease in the price of graphite (used in the production of pencils) ▪ a decrease in the price of ink pens ▪ the start of a school year▪ new technology that lowers the cost of producing pencilsD.Shifts in Curves versus Movements Along Curves 1.A shift in the demand curve is called a "change in demand." A shift in the supply curve is called a "change in supply."2.A movement along a fixed demand curve is called a "change in quantity demanded." A movement along a fixed supply curve is called a "change in quantity supplied."E.Example: A Change in Supply — the effect of a hurricane that destroys part of the sugar-cane crop and drives up the price of sugar.F.In the News: Mother Nature Shifts the Supply Curve1.Newspaper articles about specific industries can give students practice understanding the things that affect supply and demand.2.This is an article from The New York Times that describes the effect of a freeze on the citrus market.G.Example: A Change in Both Supply and Demand —the effect of both hot weather and an earthquake which destroys several ice cream factories on the market for ice cream.H. Summary1. When an event shifts the supply or demand curve, we can examine the effectson the equilibrium price and quantity.2. Table 4 reports the end results of these shifts in supply and demand.V. Conclusion: How Prices Allocate Resources A. The model of supply and demand is a powerful tool for analyzing markets.B.Supply and demand together determine the price of the economy‘s goods and services. 1.These prices serve as signals that guide the allocation of scarce resources in the economy.2.Prices determine who produces each good and how much of each good is produced.SOLUTIONS TO TEXT PROBLEMS:Quick Quizzes 1. A market is a group of buyers (who determine demand) and a group of sellers (who determinesupply) of a particular good or service. A competitive market is one in which there are many buyers and many sellers of an identical product so that each has a negligible impact on the market price.2. Here‘s an example of a demand schedule for pizza:The demand curve is graphed in Figure 1.Figure 1Examples of things that would shift the demand curve include changes in income, prices ofrelated goods like soda or hot dogs, tastes, expectations about future income or prices, and the number of buyers.A change in the price of pizza would not shift this demand curve; it would only lead us to movefrom one point to another along the same demand curve.3. Here is an example of a supply schedule for pizza:The supply curve is graphed in Figure 2.Figure 2Examples of things that would shift the supply curve include changes in prices of inputs liketomato sauce and cheese, changes in technology like more efficient pizza ovens or automaticdough makers, changes in expectations about the future price of pizza, or a change in thenumber of sellers.A change in the price of pizza would not shift this supply curve; it would only move from onepoint to another along the same supply curve.4. If the price of tomatoes rises, the supply curve for pizza shifts to the left because of theincreased price of an input into pizza production, but there is no effect on demand. The shift to the left of the supply curve causes the equilibrium price to rise and the equilibrium quantity todecline, as Figure 3 shows.If the price of hamburgers falls, the demand curve for pizza shifts to the left because the lower price of hamburgers will lead consumers to buy more hamburgers and less pizza, but there is no effect on supply. The shift to the left of the demand curve causes the equilibrium price to falland the equilibrium quantity to decline, as Figure 4 shows.Figure 3Questions for Review1. A competitive market is a market in which there are many buyers and many sellers of an identicalproduct so that each has a negligible impact on the market price. Other types of markets includemonopoly, in which there is only one seller, oligopoly, in which there are a few sellers that do notalways compete aggressively, and monopolistically competitive markets, in which there are many sellers, each offering a slightly different product.2. The quantity of a good that buyers demand is determined by the price of the good, income, theprices of related goods, tastes, expectations, and the number of buyers.3. The demand schedule is a table that shows the relationship between the price of a good and thequantity demanded. The demand curve is the downward-sloping line relating price and quantity demanded. The demand schedule and demand curve are related because the demand curve is simply a graph showing the points in the demand schedule.The demand curve slopes downward because of the law of demand—other things equal, whenthe price of a good rises, the quantity demanded of the good falls. People buy less of a goodwhen its price rises, both because they cannot afford to buy as much and because they switch to purchasing other goods.4. A change in consumers' tastes leads to a shift of the demand curve. A change in price leads to amovement along the demand curve.5. Since Popeye buys more spinach when his income falls, spinach is an inferior good for him.Since he buys more spinach, but the price of spinach is unchanged, his demand curve for spinach shifts out as a result of the decrease in his income.6. The quantity of a good that sellers supply is determined by the price of the good, input prices,technology, expectations, and the number of sellers.7. A supply schedule is a table showing the relationship between the price of a good and thequantity a producer is willing and able to supply. The supply curve is the upward-sloping linerelating price and quantity supplied. The supply schedule and the supply curve are relatedbecause the supply curve is simply a graph showing the points in the supply schedule.The supply curve slopes upward because when the price is high, suppliers' profits increase, sothey supply more output to the market. The result is the law of supply—other things equal,when the price of a good rises, the quantity supplied of the good also rises.8. A change in producers' technology leads to a shift in the supply curve. A change in price leads toa movement along the supply curve.9. The equilibrium of a market is the point at which the quantity demanded is equal to quantitysupplied. If the price is above the equilibrium price, sellers want to sell more than buyers want to buy, so there is a surplus. Sellers try to increase their sales by cutting prices. That continues until they reach the equilibrium price. If the price is below the equilibrium price, buyers want to buy more than sellers want to sell, so there is a shortage. Sellers can raise their price withoutlosing customers. That continues until they reach the equilibrium price.10. When the price of beer rises, the demand for pizza declines, because beer and pizza arecomplements and people want to buy less beer. When we say the demand for pizza declines, we mean that the demand curve for pizza shifts to the left as in Figure 5. The supply curve for pizza is not affected. With a shift to the left in the demand curve, the equilibrium price and quantityboth decline, as the figure shows. Thus the quantity of pizza supplied and demanded both fall.In sum, supply is unchanged, demand is decreased, quantity supplied declines, quantitydemanded declines, and the price falls.Figure 511. Prices play a vital role in market economies because they bring markets into equilibrium. If theprice is different from its equilibrium level, quantity supplied and quantity demanded are notequal. The resulting surplus or shortage leads suppliers to adjust the price until equilibrium is restored. Prices thus serve as signals that guide economic decisions and allocate scarceresources.Problems and Applications1. a. Cold weather damages the orange crop, reducing the supply of oranges. This can beseen in Figure 6 as a shift to the left in the supply curve for oranges. The newequilibrium price is higher than the old equilibrium price.Figure 6b. People often travel to the Caribbean from New England to escape cold weather, sodemand for Caribbean hotel rooms is high in the winter. In the summer, fewer peopletravel to the Caribbean, since northern climes are more pleasant. The result, as shownin Figure 7, is a shift to the left in the demand curve. The equilibrium price of Caribbeanhotel rooms is thus lower in the summer than in the winter, as the figure shows.Figure 7c. When a war breaks out in the Middle East, many markets are affected. Since much oilproduction takes place there, the war disrupts oil supplies, shifting the supply curve forgasoline to the left, as shown in Figure 8. The result is a rise in the equilibrium price ofgasoline. With a higher price for gasoline, the cost of operating a gas-guzzlingautomobile, like a Cadillac, will increase. As a result, the demand for used Cadillacs willdecline, as people in the market for cars will not find Cadillacs as attractive. In addition,some people who already own Cadillacs will try to sell them. The result is that thedemand curve for used Cadillacs shifts to the left, while the supply curve shifts to theright, as shown in Figure 9. The result is a decline in the equilibrium price of usedCadillacs.Figure 8 Figure 92. The statement that "an increase in the demand for notebooks raises the quantity of notebooksdemanded, but not the quantity supplied," in general, is false. As Figure 10 shows, the increase in demand for notebooks results in an increased quantity supplied. The only way the statement would be true is if the supply curve was a vertical line, as shown in Figure 11.Figure 10Figure 113. a. If people decide to have more children (a change in tastes), they will want larger vehiclesfor hauling their kids around, so the demand for minivans will increase. Supply won't beaffected. The result is a rise in both price and quantity, as Figure 12 shows.Figure 12b. If a strike by steelworkers raises steel prices, the cost of producing a minivan rises (a risein input prices), so the supply of minivans decreases. Demand won't be affected. Theresult is a rise in the price of minivans and a decline in the quantity, as Figure 13 shows.Figure 13c. The development of new automated machinery for the production of minivans is animprovement in technology. The reduction in firms' costs results in an increase in supply.Demand isn't affected. The result is a decline in the price of minivans and an increase inthe quantity, as Figure 14 shows.Figure 14d. The rise in the price of sport utility vehicles affects minivan demand because sport utilityvehicles are substitutes for minivans (that is, there is a rise in the price of a related good).The result is an increase in demand for minivans. Supply is not affected. In equilibrium,the price and quantity of minivans both rise, as Figure 12 shows.e. The reduction in peoples' wealth caused by a stock-market crash reduces their income,leading to a reduction in the demand for minivans, since minivans are likely a normalgood. Supply isn‘t affected. As a result, both price and quantity decline, as Figure 15shows.Figure 154. Technological advances that reduce the cost of producing computer chips represent a decline inan input price for producing a computer. The result is a shift to the right in the supply ofcomputers, as shown in Figure 16. The equilibrium price falls and the equilibrium quantity rises, as the figure shows.Figure 16Since computer software is a complement to computers, the lower equilibrium price of computers increases the demand for software. As Figure 17 shows, the result is a rise in both theequilibrium price and quantity of software.Figure 17Since typewriters are substitutes for computers, the lower equilibrium price of computers reduces the demand for typewriters. As Figure 18 shows, the result is a decline in both the equilibriumprice and quantity of typewriters.Figure 185. a. When a hurricane in South Carolina damages the cotton crop, it raises input prices forproducing sweatshirts. As a result, the supply of sweatshirts shifts to the left, as shownin Figure 19. The new equilibrium has a higher price and lower quantity of sweatshirts.Figure 19b. A decline in the price of leather jackets leads more people to buy leather jackets,reducing the demand for sweatshirts. The result, shown in Figure 20, is a decline in both the equilibrium price and quantity of sweatshirts.Figure 20c. The effects of colleges requiring students to engage in morning calisthenics inappropriate attire raises the demand for sweatshirts, as shown in Figure 21. The result is an increase in both the equilibrium price and quantity of sweatshirts.Figure 21d. The invention of new knitting machines increases the supply of sweatshirts. As Figure 22shows, the result is a reduction in the equilibrium price and an increase in the equilibriumquantity of sweatshirts.Figure 226. A temporarily high birth rate in the year 2005 leads to opposite effects on the price of babysittingservices in the years 2010 and 2020. In the year 2010, there are more 5-year olds who needsitters, so the demand for babysitting services rises, as shown in Figure 23. The result is ahigher price for babysitting services in 2010. However, in the year 2020, the increased number of 15-year olds shifts the supply of babysitting services to the right, as shown in Figure 24. The result is a decline in the price of babysitting services.Figure 23 Figure 247. Since ketchup is a complement for hot dogs, when the price of hot dogs rises, the quantitydemanded of hot dogs falls, thus reducing the demand for ketchup, causing both price andquantity of ketchup to fall. Since the quantity of ketchup falls, the demand for tomatoes byketchup producers falls, so both price and quantity of tomatoes fall. When the price of tomatoes falls, producers of tomato juice face lower input prices, so the supply curve for tomato juice shifts out, causing the price of tomato juice to fall and the quantity of tomato juice to rise. The fall in the price of tomato juice causes people to substitute tomato juice for orange juice, so thedemand for orange juice declines, causing the price and quantity of orange juice to fall. Now you can see clearly why a rise in the price of hot dogs leads to a fall in price of orange juice!Figure 258. a. Cigars and chewing tobacco are substitutes for cigarettes, since a higher price forcigarettes would increase the demand for cigars and chewing tobacco.b. An increase in the tax on cigarettes leads to increased demand for cigars and chewingtobacco. The result, as shown in Figure 25 for cigars, is a rise in both the equilibriumprice and quantity of cigars and chewing tobacco.c. The results in part (b) showed that a tax on cigarettes leads people to substitute cigarsand chewing tobacco for cigarettes when the tax on cigarettes rises. To reduce totaltobacco usage, policymakers might also want to increase the tax on cigars and chewingtobacco, or pursue some type of public education program.9. Quantity supplied equals quantity demanded at a price of $6 and quantity of 81 pizzas (Figure26). If price were greater than $6, quantity supplied would exceed quantity demanded, sosuppliers would reduce their price to gain sales. If price were less than $6, quantity demandedwould exceed quantity supplied, so suppliers could raise their price without losing sales. In both cases, the price would continue to adjust until it reached $6, the only price at which there isneither a surplus nor a shortage.。
晶体学课件 第四章 微观对称性
第章第四章晶体的微观对称性原子或原子团位置的对称性叫做微观对称性宏观对称性微观对称性晶体3微观对称性和宏观对称性的主要区别微观对称性和宏观对称性的主要区别：1、宏观对称性对称元素必须相交一点，微观对称性中宏观对称性对称元素必须相交一点微观对称性中对称元素不须交于一点，可以在三维空间无限分布。
2、宏观对称性中对称元素只考虑方向，微观对称性中需要考虑对称元素的相互位置关系。
性中需要考虑对称元素的相互位置关系4点阵反映了晶体结构的周期性，这种周期性也就是点阵的平移复原的特性。
对于点阵，连接任意两个阵点的位置矢量：个阵点的位置矢量R= ma+ nb+ pc，进行平移可以使点阵复原，表现在晶体结构上就是使在三维空间无限伸展的相同部分得以重复。
R可使在三维空间无限伸展的相同部分得以重复以定义为晶体微观结构平移的方向矢量以定义为晶体微观结构平移的方向矢量。
微观对称元素= 宏观对称元素+ )平移(平移轴、螺旋轴、滑移面)5平移对称性;平移轴;平移群;I P6F C (A, B)14个布喇菲点阵→ 14个平移群三斜晶系: 简单布喇菲点阵:单斜晶系：简单布喇菲点阵，底心布喇菲点阵7a'=a b'=a'=a b'=bb c'=a +c bb c'=（a +c ）/2正交晶系简单体心面心和底心点阵正交晶系：简单、体心、面心和底心点阵四方晶系：体心和简单四方点阵三角晶系：简单三角点阵8六角晶系：简单六角点阵立方晶系：简单、面心和体心立方点阵2、螺旋对称轴A: 4; B: 4金刚石0,10,10.50751;30.50.250.75B0.50.250.75A 0,10,10,10.59n=3s=0,τ=0,3次旋转轴s=0=0s=1, τ=T/3, 3,次螺旋轴,右螺旋;,,1s=2, τ=T/3, 3次螺旋轴，左螺旋。
,,次螺旋轴螺旋215n 4次旋转轴n=4s=0，4次旋转轴；11/4T s=1, τ=1/4T ，右螺旋轴41；22/4T 双螺旋轴s=2, τ=2/4T ，中性螺旋轴42，双螺旋轴；s=3左螺旋轴s=3, τ=3/4T ，左螺旋轴43。
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网上流传的高校毕业生工资排名
2007年前10名
1
2
大连外国语学院
电子科技大学
5050
4900
3
4 5
中央财经大学
中央戏剧学院 复旦大学
3916
3875 3863
6
7 8 9 10
北京外国语大学
中国科学技术大学 西安交通大学 上海外国语大学 上海交通大学
3717
3700 3682 3633 3596
(1)
Wage
(2)
TWC
(3)
MWC
(4)
(VMP) MRP
(5)
0 1 2 3 4 5 6 7
$1.00 $2.00 $3.00 $4.00 $5.00 $6.00 $7.00 $8.00
----$2 $6 $12 $20 $30 $42 $56
--$ 2 $ 4 $ 6 $ 8 $10 $12 $14
W0
SL=MWC=PL
DL=MRP=VMP
Q0
Quantity of Labor Hours
19
配置效率（ efficient allocation of labor ）
• 富有效率的劳动配置是指：既定的劳 动总量给整个社会带来了最大数量的 产出。 • 富有效率的劳动配置意味着：不同劳 动市场上每一劳动的边际产品价值 (VMP)相等，都等于劳动的价格。
• 三资企业工资仍最高 • 低技术含量工种价位走低 • 工资与性别关系不大
7
一、劳动的供给
• 供给的决定因素： • 工作时间
8
劳动供给 (一)
消費
438,000/P C
B E1
365,000/P Y0
U1
Y1
E0
U0 A 365
0
D1
D0
休閒(天)
圖 8.2 工作的選擇
• 在图 8.2 中，横轴是休闲的天 数，纵轴是消费。 • 图中 A 表示一年当中每天都休 闲而不工作。B 则表示 365 天 均工作，假设工资率为 1,000 元，商品价格为 P，则全年消 费为 365,000/P 单位。 • 因此： • 消费 = 1,000*(365 X)/P • = (365,000 - 1,000X)/P • 真正影响劳动供给量的是W/P。 称为「基本工资率」,，以小写 的 w 代表之: w = W/P。 9
第13章
劳动市场
1
第一节 工资决定的基本理论
• 工资如何决定？
– 劳动供给 – 劳动需求 – 劳动市场结构
2
美国：按行业划分的平均小时收入, 2003
行业 金融、保险和房地产业 公共管理 矿业 运输、仓储、信息和公共设施行 业 制造业 建筑业 服务业 零售业
小时收入 $20.99 20.22 19.81 19.27 18.51 17.31 16.53 13.21
$ 10 $ 9 $ 8 $ 7 $ 6 $ 5 $4 $3
买方垄断情况下的工资和就业
• 企业的边际工资成本 MWC 要高于劳动的供给曲线SL. • MRP ＝ MWC 时（a点）实现 利润最大化，此时均衡的劳动数 量为 QM • 此时，工人愿意接受的工资 率为 WM. • 与竞争性的劳动市场相比，企 业支付的工资率较低(WM < WC) ， 雇佣的数量 较少(QM < QC). WC WM b DL=MRP=VMP Q M QC
– 进口会遭到削减，在全球范围内提高消费者支付的 32 价格
限制劳动供给
Wage rate • 工会通过限制劳动的供给( S0 to S1), 导致均衡的工资率上升 （ (W0 to W1)，但是均衡的劳动数 量会降低(Q0 to Q1 )。 S1 S0 W1 W0
D0
Q1 Q 0
Quantity of Labor Hours
31
世贸组织、贸易自由化和劳工标准
1999年11月，在西雅 图开会的WTO面临 数万人的抗议示威。 WTO并未致力于解 决有关工人权利和环 境方面的问题 工会极大地介入了西 雅图的抗议活动。
• 将劳工和环境标准作为国际贸易协议的一部分，只 能让发达国家的工会工人受益。
• 工业发达国家的消费者和发展中国家的生产者和消 费者则要付出高昂的代价。
5
2008年毕业生工资排行
• • 1 中国地质大学 4980 （以地矿、珠宝类为主，毕业生 主供石化勘探、珠宝相关企业，起薪4000以上） 2 电子科技大学 4500 （以电子通讯类为主，毕业生主 供电子通讯如电信、网通等企业，起薪3500以上）
财经类为主，由于背景雄厚， 大部分毕业生进入国家相关部门，起薪3000以上）
29
增加劳动劳动需求
• 工会使劳动需求增加 (D0 to D1), 这样工资率上升(W0 to W1) 的同时，就业量也上升(Q0 to Q1) 。 Wage rate S W1 W0
D1
D0
Q0 Q1
Quantity of Labor Hours
30
工会如何增加劳动需求
• • • • 增加产品的需求 提高劳动生产率 影响相关要素的价格 增加雇主的数量
Quantity of Labor Hours
26
Wage rate
MWC
SL=PL
a
c
•缺乏效率的劳动配置使得社会 损失了相当于三角形abc面积的 利益。
职业棒球运动中的报酬和成绩 • 1976年以前，职业棒球运 动存在买方垄断
– 禁止选手在公开的（竞争性）市 场上待价而沽 – 薪金大大低于其MRP
18
完全竞争市场上的工资和就业
• 在完全竞争的劳动市场上， 企业是“工资接受者”。它面 临的劳动供给曲线 SL=MWC=PL, 是过W0点的水平 线，是完全弹性的。 • 如果增加雇佣一个工人的边 际收益产品(MRP)比边际工资 成本(MWC)大，企业就会增加 雇佣工人。 • 在 MRP=MWC 的时候，企业 实现了利润的最大化，此时雇佣 的劳动数量为 Q0 。 Wage rate
Quantity of Labor Hours
11
劳动供给的决定因素
• 其它工作的工资率
– 如果其它工作的工资率上升 (下 降), 那么劳动供给会减少 (增加)。
• 非劳动收入
– 如果非劳动收入增加 (减少), 那 么劳动供给会减少 (增加)
• 工作－闲暇偏好的改变
– 如果对工作的偏好增加 (减少), 那么劳动供给会增加 (减少).
• 为简化分析，假定此时产品市场 依然是完全竞争的。
24
劳动市场买方垄断
• 劳动市场上的买方垄断者面对向上倾斜的劳动供给曲线，随着雇佣 工人的数目增加，买方垄断者必须支付更高的工资。 • 企业的总工资成本 (TWC) 等于工资率乘以劳动雇佣量。 • 边际工资成本 (MWC) 是指雇佣最后1个工人时所支付的工资成本。 • 企业利润最大化的条件时 MRP = MWC ，最优雇佣数量为3。 Units of Labor (L)
4 中央戏剧学院 3765 （以戏剧演、导为主，由于商业 介入强势，灰色收入早已倍超工资，起薪3000以上） 5 复旦大学 3700 （以出国留学加创业为主，由于上 海的西化过度，以进入外企为主，起薪3000以上）
• ……
•
18 对外经济贸易大学 3169
6
行业工资排行（2006年）
• IT、交通运输、金融列三甲
– 劳动供给方面的原因
• 与生育高峰相连的劳动供给大幅上升 • 女性劳动参与率的迅猛增加 • 移民浪潮
美国1979-2003年间实际收入的下降和反弹
– 劳动需求方面的原因
• 国外的竞争压力 • 工联主义的衰落
• 1995年以后，实际小时工资上升
• 经济繁荣促进劳动需求增加 • 劳动生产率提高刺激劳动需求增加
Quantity of Labor Hours
22
Wage rate b W0 a c SL=MWC=PL
3. 劳动市场的买方垄断
（ monopsony ）
23
劳动市场的买方垄断
• 买方垄断是指劳动市场上只存在 一个雇主。
– 买方垄断者（垄断性雇主）在增加 或者减少劳动雇佣量的时候，能够 完全控制其价格（工资率）的高低。
16
劳动供给的变化
Wage rate • 假定移民劳工大量增加。 • 这会导致劳动供给曲线向右 移动 (从S0 移动到 S1)。 S0 S1 W0 W1 D0
• 均衡的工资率将降低到 W1 均 衡的数量将上升到 Q1.
Q0 Q1
Quantity of Labor Hours
17
• 1979-1995年间，实际小时工资和周工 资出现了下降
劳动供给 (二)
消費 消费
438,000/P C
B E1
364,000/P Y0
U1
Y1
E0
U0 A 365
0
D1
D0
休閒 休闲( (天 天))
图 8.2 工作的选择
• 我们可以把消费与休闲当成两 种「商品」看待，绘出劳动者 的无异曲线。 • 无异曲线和 AB 直线相切点， 就是劳动者的最佳抉择。 • 当工资率为1,000 时，无异曲 线 U0 和 AB 直线相切于 E0 点。此时休闲天数是 D0、工 作天数是 (365 - D0 ) 。 • 假设工资率提高为 1,200 元， 此时选择组合线变为 AC。无 异曲线 U1 和 AC 相切于 E1 点。 • E1 相应的休闲天数减为 D1 天、工作天数变成 (365 - D1) 天，较工资率为 1,000 元时 提高了。
3
中国：毕业生薪水排行榜
• 一张“2007年毕业生薪水排行榜”在我市各 高校校园网站悄然流传。榜单上列出全国89 所高校毕业生薪水具体数据 • 榜单上一共列出了89所学校薪水数据。其中 大连外国语学院凭借平均月薪5050元高居榜 首，对外经济贸易大学以3169元居第18位。 清华、北大两所高校却意外被排除出前十位。 • “薪水榜”最早的出处是2007年2月12日的 “中国校友会”网站，没有署名。以前也流 传一个2005年的排行榜。 • 一些家长甚至以这些数据作为高考填报志愿 的依据。