真三第張四第
日十二月九年牛芮宴
育教僑華
欄專書預題試考曾擧中文
+
物理科
·梁海明。
PHYSICS (1) By H.M.Leung
INTRODUCTION
The object. of this column is to help the studente n the preparation of the Hong Kong English School Cer- tirioate Examination in Physics. The pattern of this column is the question-answering type. In each Wednesday! the topics for revision are given, followed by a set of questions for the students to answer. For the purpose of familiarity to the type of questions of physics in the H.K.E.S.C.E., each question is set in the way as that of the questions in the H.K.E.S.C.E. in the past three years. Students should plan to answer each ques➡, tion in half an hour.
There will be approximately 28 weeks before the School Certificate Examinations in 1967 from now on, therefore, approximately 28 sets of questions will be given to cover most part of the syllabus in the sub- ject of physios. It is suggested that students make
se of this column in the following ways.
(i) Read this column carefully.
(ii) Review the indicated topios in the text books
or notes of physics.
(iii) answer the questions provided.
(iv) Compare the suggested answers printed in the
following Wednesday.
A brief revision in measurements of maas,length, ind time:
Measurement-- All measurements in physics are related to the quantities of length, mass, and time. In the Metric system, the unit for length is metre, for massia kilogram, and for time is second. We call At the M.K.3. system. Sometimes we use the 0.0.5.
system (centimetre, gram, second). The fundamental unite of length,mass and time in the British system is F.P.S. (foot, pound, second). The reader is suggested to re- view the multiple unite, sub-units and the conversion of the Metrio to British system and vice versa. As ve know, the F.P.S. system has the disadvantage of incon venience in calculation.
(a) Measurement of length. When accurate mea- surement in length is necessary, we use an instrument called Vernier Calipers. Usually, the scouracy of the reading of a Vernier Calipers is correct to 2 places of decimals in centimetres or inches, and the accuracy of y the reading of a micrometer screw gauge is correct to 3 places of decimals in centimetres,
(b) Measurement of mass and weight- The reader is reminded to distinguish the difference between mass and weight. The mase of a body is the quantity of mat- ter it contains whereas the weight of a body is the for oe with which it is attracted towards the earth, That is, the weight of a body is due to the gravity. Theres fore, the weight of a body varies in different places, but the mase remains unchanged. The unit for mass des kilogram or gram in the Metric system, and the unit for weight is kilogram weight or gran weight. One gram weight means the pull of the earth on a mass of 1 gram.
The instrument for the measurement of mass is the beam balance which is to be familiar by every seocndar #tudent, The principle that the bean balance can be used to measure the mass of a body is that weight is propor- tional to mase, and we can measure the mass of a body by comparing the gravity on a standard mass. The instrum ment for the
vance Measurement of weight is the spring balanoe. The principle of a spring balance
the extension of a spiral spring force applied to it within the the spiral spring.
in the fact that
ReBortional to the
of elasticity of
(c) Measurement of time- The unit for time is the solar day which means the interval between two successive transits of the sun across the meridean. Since the length of a day varies, we use the average, that is, the mean solar day. The mean solar day is too large a unit, hence we use the mean solar second which is
of the mean solar day,
86400
Suggested revision topics this week!
1. Fundamental units: masa, length, time.
2, Measurement of length, area, volume mass and weight,
3. The spring balance, the beam balance.
4. Density and specifio gravity.
Questions.
1. (a) Define and distinguish between the terms density
and specific gravity.-
(b) Describe briefly one method of finding the speci-
fic gravity of (i) sand, (ii) liquid. Point out the precautions to be taken to obtain a good result.
(c) A specific gravity bottle of mass 50 grams weighs
100 grams when filled with water; 88 grams when filled with a liquid; 140 grams when it contains 55 grams of a powder, the remainder of the bottle being filled with water. Find (1) the density of the liquid, (ii) the density of the powder. (a) What volume of liquid of specific gravity 1.6
must be mixed with 2 litres of liquid of specie fic gravity 0.75 to make a mixture of specific gravity 1.15, assuming that there is a contrac- tion of 5% on mixing?
(b) An alloy consists of 60% aluminium and 40% mag- nesium by weight. What is the density of the
alloy? Density of aluminium 2.70 gm/0.0.1 0x magnesium 1.74 gm/b.o.)
(0) In an experiment to find the density of air, the apparatus consists of a round-bottomed flask fitted with rubber stopper carrying a short glass tube in which there is a piece of zubber tubing and a screw clip.
A little water is poured into the flask. The clip is removed and the water is allowed to boil vigor ously for a few minutes so that the air will be ex- pelled from the flask. The clip is then fastened⠀ tightly. After weighing
A
'AH KIU YAT PO CITY HALL
「問專習預題試老會學中文中
數學科
·喬仲强。
數學本来是需要思考的一種學科,如果思想不够 精家,則容易導致錯誤之结果,而詭辯之術乃得乘虚 而入,於是“是非不明,真假莫辨為使讀者易於明白起 見特選錄數學上“詭辯法”之例,以証吾說
{(例一)試証任意三角形必為等腰三角形 A
[{Z ko) ·A`ABC
(作图及証明)
#) AB-AC
“作2BAC之分角线使典BC之垂直平分
# DK #*** 111 KB 14 AB, AĆ Z KXB KY.
XX KB, KC aj
}
242 (BAK ÉS A11)
2 ZAXK=2AYK = M L
(垂线成直角,凡直角皆相等)
3
AK= AK (#)
4 st s AVK 2 A AYK
-
5 KX=KY AX=AY (H&L)
(rt a. – Afié - ILA 4;
6 KB = KC (* £ ¥ ± 2 §.
至两端等距)
8
X
(图一)
13 4 § 24
三期嘉
SEREKBEN
:夏普博士與李西博士
拜戏大學生物化學說準,商曹大人。
白有隔邳白質方面之生化學颛合會之第一內外人士和臨 港大系之邀,將濶投,他的媽論。 DEXTEEN GBEZRAZKE EUFSILANI
化學•
THE• ZERIKE
英
SEXYEEBE 卄九两晚,下午七時
將在兩間大學講學 臺灣參育的
一,故證照師開很燬,
1二月一十年六六九一膺公年五十五國民華中
*UNSHGAN SA MË
X-TRZEŁ
→ TË
RE
FA
中學會考試題 不宜過度艱深
·教育界認爲不應大淘汰
中四班學生・
【六七年度之山藝文中寒,管所生
KEFE THE WIDZETE
BISONER
15A ISEENNE **350=0,
KE - ZERVA STOCKEY=
【開會長王幸利表示,學生之校,有九 不論中英文會考,共四著, 新亞學生會 MENSKE ******* • (E).
三英國學者兩人訪港
。目前茶中會考委骨一面,應予湯在云
KNEKKERE
BER.
內同波的明一我
人热
*
2
稠的数片生篇。风
FLIR
賽會
,英馁。
1967
英文中學會愛試題預習專欄
(图=)
化學科
(-)
***, ska är! *
7 <KXB = < KYC = rt 2 (*1A, à¥)
AK X Bert AKYC (RHS) ax=CY(全等形之对应边
AY+CY (1)
१.
10
AX+ BX =
AX- BX AY CY
(如图)
(等量公理)
即
AC
例)試計通銭外一 作图及証明)
作P两园使相柊
A卖,又作两园之直径 ABRAC
All BC J j i la X D
RE XB AD AE, B
£1 CADB=rti
(a) =)
LAECENt <(# 2 8 0 ) )
ADI BC
故過膜呵作
設 两边来以a 各滅法
分解因子
AEL BC
(我线定義)
BCで岳域共有的
-b...
。
a-bal-f2
(a+b) (a-b) = b (a - b)
两边除以(a-b)
ul b N #Z a. (B&a=f)
A
除以!
(例四)設
等量相減得
()乘以名
移項
分解 開方
a+b= b
f+b=f
* s=ath ---anod!)
s-a
b
fs = b(a+b)
b s = a b + b
bs=a(s-a) + £*
CHEMISTRY (1)
1. What does the filtrate consist of when (a) salt solution, (b).
chalky water, is filtered? What does the distillate consist of when (c) sugar solution, (d) water mixed with methylated › spirit, is distilled?
ANSWER (a) salt solution
(b) water
(c) water
(d) methylated spirit mixed with a small amount of water,
2. Give the name of a solvent for each of the following
substances:
(a) Grease or fat, (b) sulphur, (e) iodine, (d) paint, (e) rubber, (f) common salt. (8) tar (h) shellao
ANSWER (a) Carbon tetrachloride
(b) carbon disulphida
(c) alcohol
(d) turpentin
(e) benzene
(f) water
(g) gasoline
(h) alcohol
3. State the effect of rise of temperature on the solubility in]
C LIBRA
-as-a+ka
bbs.
第二次預習題
(1)上述四例题,均有錯誤之處,以行其詭辯之術,試分
别指正之。
(J2) 何謂運走理?对定理? 对逆定理?試舉例說明 (B)已知定理“△ABC中∠BAC之平分线交BC 於D则
2.試寫出並証明其逆定理”
AC DC
(3) 設△ABC篤正三角形,C為AB上饪-奌,遇C作直线加垂 直於 cc!又遇 A. B的直线p,g垂直於AB而交批於A及 B.求証 △ABC為正三角形
) 設為口园半之長,AB笃遇0之直线两奌,且OA<%,
OB > N, X ōA· ōB =",若P及P為0园上任=奌求证
PA PA·
PB.
'5) 設:a.lc老一個三角形三边之長,且有下列間係:
試証此三角形為正三角形,
this when cold, we clip is released and air rushes into the flask, which is then weighed again, Volume of water remained is measured and then the flask with the tubing is filled com-
pletely with water. The following results
tained after doing the necessary weighings:- Weight of flask with air expelled-141.82 gm Weight of flask after air is admitted-142.43 gm Volume of water remaining in flask 42 0.c. Volume of water completely filling flask-550 0.9′′ Find the density of air,
water of
(a) common sale, to potassium nitrate, (c) air,
which of (a) and (b) can be purified by recrystallization?
(4) The solubility in waves antreased only silently with ris.
of temperature.
The solubility in water increases very rapidly with rise. of temperature.
At 70°C, the solubility is more than 10 times its solubilft at 0°0
(c) The solubility in water decreases rapidly with riss of
temperatura. Potassium nitrate can be purified by recry stallisation.
The solubility of a certain salt 14 50 gms. In 100 gms, of water at 1000, and 11 gus, at 30°C, What weight of the salt would crystallise if 50 gms. of itu saturated solution-were-cooled from 100°C to 30°C 7
Solubility of the salt at 100%
50 gms, per 100 g of water e. Weight of salt. in 150 gms. of saturated solution at 10090
50 gms.- Weight of salt in 50 gus. of saturated solution at 100°C.
ad weight of water in the solution
Solubility of the salt at 30°C
50x7523
gns.
16% g. (50-1634) 8)
33K gma.
11 gs. per 100 gms]
u water
• Waight of salt that would saturate 335 ms. of water at 30° C.)
11 x
3.gos.
Hence weight of salt that would crystallize from the solatfor
(1633-336) gris,
13:இம்
5. Classify the following substances as elements. compounds or
mixtures.
(a) oxygen, (b) gasoline, (c) freshly distilled water
(g) water gas, (1) common salt, (1) sugar. (zlucose).
ANSWER
sulphur, (e) gunpowder, (f) air, hydrochloric acid.
Elements
oxygen.
sulphur,
freshly distilled water Sugar
Mixtures
gasoline
gunpowder
water gas.
hydrochloric acid).
ensimon balt
6. Name all the processes used for obtaining the separate componenta
in the following mixtures:
(a) sodium chloride and water,
(b) potassiumsulphate and sand;
(+) ammonium chloride and potassium chloridej
(e) iron filings and chulk;
(e) calcium sulphate and water,
(F) a solution containing two salts with different solubilities,
potassium chloride and potassium chlorate,
.
ANSWER (a) Distillation ...
(b) Solution, filtration, evaporation, (c) Sublimation,
(d) Removal of iron using a magnet
(e) Filtration.
(r) Solution, fractional crystallisation
QUESTIONS FOR NEXT WEEK.
1. How would you show experimentally that air contains (a) watër
vapour, (b) carbon dioxide, (c) oxygen?
Describe one experiment by which you could determine in the laboratory, with reasonable accuracy, the percentage by volume of oxygen in sir.
2. How would you show that: (a) sulphur dioxide is an acidic oxidej (b) magresium oxide is a basic oxide, (c) zinc oxide is both
basic and acidic ?
Name three substances besides potassium chlorate which will give off oxygen on heating and say what is left in each casel-
Substance,
Residue
Mercuric oxide is heated strongly in a test-tube and then cooled io air. What changes would you be able to observe ?
Page 15Page 16