1986-12-06 — Page 28

華僑日報 All

頁四第張七第日五初月一十年寅丙圈夏

refers to the quantity, demanded or Mr. a for

1987中學會考 試題預習專欄

Price

經濟(十一)

明德出版社, MILL & DALE PRESS

Revision Exercises

for

Cert: Exam. (1987)

ECONOMICS (11)

Demand

T. The definitín of

demand;

The demand for a commodity does not only means the need or the desire for that commodity. If refers to the saount or quantityofit. that people are willing to buy at various prices, It is the willinguess coupled with the ability to buy that commodity at a price,

To distinguish demand from wants and need, demand fora. corimodity is backed up by the ability to purchase it. In

economic theory)

demand always menuis

effective demand,

II.Demand Curve?

There is a tendency

for a buyer to buy.

more or a commodity at

& lower price than at

a higher price.

-Ludividual demand means the quantity of the commodity ilerjandied by an individual.

Market denand meang that the total sum of demand for a commodity by all individuals in the market

An Individuala demand for a commodity at different prices during a given period of time can be compiled into a schedule.

Price of

orange (8/per

anity

Quantity demanded of Mr. A for oranges fer month

1.5

5.

8

1.0

童言

0.8

19

0.47

20

-0.6

23

0.5

27

28

0.3 0.2

Putting the above table into a diagram adowoward aloping curve can be drawn, The curve represents the state of depand at a particular time. The vertical axis refers.

to the price scale and

the horizontal, uzÍ B

̇職苑:

Individual

Deusid Curve

For orange

5 10 15-2025 30 35

Quantity demanded of

Mr. A For Orange

The demand curve. clearly shows that the higher the prices the smaller quantities Fung would be demanded. Its slopes downward and it is moving from left to right, introducing tre law of demand.

The law of demand states that the lower the price of a

commodity, the greater will be the quantity demanded In other words, the quantity demanded by an in- dividual or the whole. market is inversely proportional to the price of that commodity.

Therefore, the aggregation of the demand curves of all individuals in the economy is called market demand curve.

Its shape is likely 您好运北:复twill also

slope downwards from

left to right, as

show in the below diagram.

(Price)

Market deo and

Quantity demanded for a commodi ty

FIT.Change in demand

“A enange in demand" is different withwa change in. quantity demand". A change in quantity demanded means the changes of the quantity demanded in respect of a range, of price changes: It is the response, tọ changes in the price of the commodity and is the movement ulong the demand curve.

A:change in demand means that a greater amount or smaller amount of goods ano servicen is demanded without any changes.

in the price.

A change in demand involves a shift in the demand curve.

if the curve moves towards the left- (from DD to DqPq). then there is an

increase in demand,

as shown in Fig. A.

有部分鐘

WAH KIU YAT PO

Price of the commodi ty

Quantity demanded

for a commodity

If the curve, noves backward from DD to D¿Dit is.

that there is on decrease in demand as shown in Fig. B. Price of the commodity

Quantity demanded for a commodity

IV Factors affecting

change in Murket demand.

1. The tastes and preferr ences of the consumers

It is said that the taste and preference of the copauwers would affect the purchase of goods and services. Every household is different, and ever -members of the same

Zumily have different tastes and preferences.

Riligious, soci01. and econonte factors can affect the choios of consumption in food, clothing living conditions, entertainment and recreation of the

citizena. Since, there. may have different. racin): group

country, the summation of the individual demand plays a: anjor part in deciding total demand for a corrodsti or service.

Nowadays, consumers are mostly affected by the advertising:

strategies promoted by firms. They day be attracted by, the Laxionable commodities:

The incone of the households

: Family income is one of the major

factor in determining family's consumption, Those -higher Licome families will apeid more on consumption

·goode. The reul income. of the families determine the

household purchasing power. If there is inflation problem in the economy, the general price level. would be increased, leading to the

decrease of purchasing pover of the house- holds. As a result,

分後易話

一盡後,於致高

有例賴:

街出来區 商來火在面

報日僑華

there must be less. quantity demanded.

If there is a

general increase in

thy income of the

society, an increase

in deriand will be. caused:

3.The necessity of the

commodityG

If the goods are necessities and they are demanded by everyone in the aociety, the charge in demand will be reduced bo a certain extent. For examples, food and drink are necessities in our life. Some goods, such as tobacco and alcohol, are habit-forming.

The prices of other

If the goods are closely substitute for one another, the price of the commodity would be seriously affected by the decrease in

substitution gueda. Even then the goods are not substitute to each other, the slemand. for a commodity would be affected because there are many ambag possible: altomatives of satisfaction avail- able to the

5.The size of the

population of the country

If the country is densely populated and the population as increasing, many people are going to be fed and clothed. A§‚a result, there are greater demand ́of the

food, drink, clothes audhuusing in the society, and the demand for necessity goods will continue to increase

by

6.The distribution of

income "anong, the-

population of the

government:

If government tries 請ue tax aystem to eliminate the gap

between the rich and

the poor, greater. equality would be achieved.

Taxes may be imposed to reduce the demand for a commodity. For example, excise duties have often been

imposed on imported good so as to reduce the demand for them,

物理(十一)

MILL & DALE PRESS

Revision Exercises

for Cert、Exam. (1987)

·PHYSICS (11)

4.2 Vector and Force

A vector is

quantity which has

both direction and

magnitude g

displacement, velocity,

求要民居司公話電

六期星

日六月二十年六八九一展公年五十七國民華中邨新門屯育教

force, momentum etc.)

A scalar is a quan-

tity which has

magnitude only (e.gr.

length, area," mass, energy, power etc.)

Forcea are vectors.

A force is well specified if its megnitude, direction and point of applica tion are given.

The resultant.: (vector su

several forces is force which would produce the same effect as the for

ADDITION OF VECTORS (a) Triangle method.

Draw the two given

vectors and"

after one (1.e, the tail of one. betug. attached to the arrow head of the other. Then the rpaultunt R can he represented by the vector starting from the tail end of F to the arrow-head of Fyns: shown. in the

figure.

(b) Polygon method

For several vectors, the resultant can be obtained by applying. the triangle.method

successively,

Parallelogram method

Tang

+F cose

Analytical Method

Resolve all the vectors into two chosen mutually perpendicular directions. (say x-direction and y-direction). If the.. vectora Fa Fo

make angles 8?

respectively with

the x-axis, then

Premagnitude of

nent of the resultant A

五而不公 買個嗜

工城 迄業 低情,

定中月行實否是證照

上所 南西 集函 災仁現會免,

實驗結亭話電設灣蝶蝴

感, 指民 地出 審堂 屯公 電慈 覺不出

【話故 ̇徨是

插進入

門時由

年月進用期題眅時該 興久劃場擺。定將臨 的區

Z Fysmagnitude of y-coupe-

nent of the resultant R

sine Fsine

force triangl

the corresponding.

Hence

Hen

- √ (XFx)2+(?P¥)

and

tand

PY ΣΕ

where is the angle which the resultant R. makes with the Taxi a..

ple; Find the result-

aut of the forces shown in the figure.

R12N

12N

4.50

157

30

60°

10N

0 Rx-9.5048N

Solution: (A)By Calculation

Rx=ZFx

-15cas30 2c0845

9.5048N

12sia450

-7.3252N

RI+RY

9.5048)*+(7.3252)

tang

7.3252 5048

(Ans.).

0.7707

37°37*

(Ans,)

siné

whenever three forces are in equilibrium, they must be concurrent and coplanar

(B) If a system "con="

current forces is in equilibrium, then their resultant is zere or the sum of their component é

along any direction is zero. It follows: that

2Fx=0 and £Fy=0!|

Relative Velocity. The velocity of a body" A relative to body is given by

(B)By Graphical. Method

The magnitude of the resultant R is found by measurement

R 12N

37.5"

It is the velocity of A as observed by B.

the veloc B lies, of A and B. observed by a stationary person.

Example: Two ships and

B 4000 apart

begin to sail due

east and due

south at 12s

AKU 16ms

respectively..

Find

"(a)-the velocity of

A as ohaurved by

avend on B

(b) their abortest distance apart Sulution: AND

(a) The velocity of a as abserved by n man on

B is the relative velocity of A to B.As shown in the figur

12N

(ie the resultant is 128 and at an angle of 377 with the x-axis)

Concurrent Forcés

A body is said to be EQUILIBRIUM if it ismat rest or moving with constant speed in a straight line.

(A)Triangle of forces:

If three concurrent forcea (says

end F)are in equili- brium, they can be represented both in magnitudes and

directions by the three. Bixes of a closed.

triangle taken in order. The converse is algo true.

concurrent forces

也變不谢伏

鈉諾 通妨得願劃定診

海高車 你們 用戶一而朗 教爲輛,詔 天及群區 政

業墬入會,討會英 送元, 戶若 特代論主。

中居。据老

-初行,於街街署建性在,實將於於時

善年创由擺,動人現水域,

#完預工光時於司以工性·代稱市販

按算 ·程月 街工 ·的配興街·化興·政遥及合月完, 用及今現及市窟 情合建市 街建 继入元當一战街

八十歳月 能的 善個時,個 正大街政及工

七二極啓·茹、小器,但永計市上家用程橋!

圾南,拉二的元的的 傑 個街投資 分, 戶的約月

收及辦 向位 百月至月市署 小市枱格處面,小有 第一本設共出七租八租值 已此型拍位人 东區 將販一

|站苡處 有二時十是百·是租 經外 枱位,十矜域可,九時

等城一两 ·街五介元介金辭,及包, 上市 透包

另物起二市元乎,乎, 定差 等一括彩月政入括位市 和料卸十除不二小四街 街的。百七加 ·激送 街廿

四大 草市 市物

個存、個、。元柏 五枱 ·抬業

位處街外小至位十位位信二個頭 合朗 機商 格

投,求給委王仍然

<降香員

設便 低港會 元邨、有麻 黎地 廠招 元工不明的 明家邨

∝袜朗業久・區酎 始,仍近 但更 工邨以 議劃將該有飽

元售司九個

恩級 勞朗,前仍百由最 ,的“力交對景 對元每近合 核發資通於察元,平行 鹿原不有到加 方钱 司 短價些樂 工價 米公 反力缺,燦覩業

邨能

述量 ̇效上中一款

只天即

〔三)有關「觀瞻一問題:辦事處常常

日本苑的住客使用停車媽都是. 理員更是同這些司機十分老友記, 涉及檢驗他們離開此地,部份資

·理員及護衛十分清楚,但沒有千 本苑的地方。這種情况本苑的管 及更換零件,入油等,常常弄污 呎的小路,進行裤洗車輛,檢查 戶,他們非法佔用已有車牌編號的泊車位外:强調要求本苑業主保持大臣的外觀統一及潔

黃瑞 的士佔用停車場褓姆車發噪音

樂雅苑居民表不滿

五于米;而女子組 元朗大馬路冗朗政務處

决,請辦事處多留意。

【終她執行,其他一些

公司及一定要貫徹始

;執行時是要授權給有關的護衛 ,對他們會有一定的嘛誠。當然 通知,要他們快速繼開,其實是 沒有用的,最好是立茲用鏈鎖車.

及 業衙里只在他們車頭玻璃貼上 (六)補-

第八點:除上逃時間之 外,晚間更多非法泊車,辦事處

*不所:本小侵物

成付苑小點

訴比的業的

呢. 例簪 主意 以方

樂理辦見

可感否希 本考!

,有的人

本關秩的能德

眼 苑部 序方 辫福 些

堂言群

幹有一輛褓娒車,女司機每天都來往本有:爲對嗎?我們是每月都要交管理費,當然要 施來交車,檢查車輛等,毋須弄污及阻碍木處大部份是在地下,由各該案貝的當室傍 (一)有等車輛經常發出强大的「按」礙通這,但却有礙觀髏,辦事處路公,你認·委員會投訴呢? 職員來巡視,特别是在上述時間內。 紙、摺椅,等等的雜物放在門外,雖然不阻,成果不成比例,是否可向消費者 苑的地方。其寶辦事處應不定時及定時的派,迫使可出入,他們常把一些物件如魚缸、報 業主所付的管理費更成爲付出與 車場內有大量空位,他们可以使用上述的設,把大件的垃圾放在梯間,此外,管理员的住一法及優點,以求改善本苑的秩序 用。其實本苑的室内性市場及樂華北邨的停焚化「元實一的桶放在梯間,更有部份來王 到、辦事處方面應參考別人的游 間都空器,但並不代表可以任由宽外人士伯 在門口外发上一地王」等的甜,又把做,爲甚度我們不能辦 毎月付出費用給事處,雖然日間大部份時,學,但本人更加認爲內部也重要,部份戶主 私人的樓宇,如淘大花園及德蘭

要求房署加强管理

迎假

買朗 時日長度 麵晢 朗底滅

名:名之

女額居

開公司

組開參

百報

年干男

跳廚米子場

於明年五月至九月閻 服務爲止。

談然 家人 入招:

、邨帶根,聘 的邨您動 內

需力 公要本很工勞路

請些規種知在的力元决於法不 廣公 已火道 元做,朗的分,使 港 告共准與 才工朗告 只區 問按但不 以打新署故邨住夠廠有。是期間

加內·家市 工廠 的深家足工一区

全述一合自是作該識

4方兩家純行經

後的的千分

九廣遽路公司發言 核運抵本港,並進行裝

共廿五輛明年中運到

士,作杓佢选路接駁之將由輕鐵及接駁巴士

據悉,莲粉科已成

·逾二千五鄉巴士,駁巴士在取代九巴的過

每部長九點七公尺,可程,得以有效及順利地

6mg

£Uma

(ans.)

52

0.75

the ship A seems to aeil at 20ms-1 in the direction

N36 52 E as observed by a man on B.

(b) The shortest distance

apart.

BC

=A8sin(90".

=(4000)(0.8)

3200g

遙星期六列出

元朗市西北盛商戶及居民拉起橫額,

反對建行人天橋令他們上落不便,此費資

T

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