1966-01-19 — Page 23

春健健

日八十月二十年日乙脚野

WAH KIUSTAISTO & 36 – SMESTAD UN

一九六六年

新墨科

韓試題預習專欄 試題預習專欄

(=)

物理科

̇陸永熾、

PHYSICS (3)

By Mr. Luk Wing Chee

Since

(a) Archimedes' Principal states that when a body is wholly or partially immersed in a fluid it experiences an

upthrust equal to the weight of the fluid displaced

(b) Let M be the mass of the brass in

density"

"weight"

11

10

4

IL

d.a.

Ria./c.c

昨

肉

dyne.

11 "aluminium go.

V

be the volume

D

Mz

11

MAAS

帖

volume "

•

cc.

denatvn:

#

1

gm./c.m

+

st

1

dýnee

D'

M'g "weight"

Unt.hrupt on the brass object (四)g dmea了

。

D

Upthrust.on the aluminium object gaynes

Since

(M2-8) (M's -

Apparent weight,

ㄓ

(1 - )

- M (1-2)

(1

from equation":{}}'

第二次複習試題解答

喬仲强

(门在定园口中,AB為足球,AP美動,以AB,AP鄰边作平行 边形APCB,當P桌移動時,試求此平经四边形对角线安鬓之軌』

(B知)AB萬口园中定弦,AP為動弦,

APCB蓴平行四边形,AC.时分牙M.

(冰)當P真移動時,M&M鱿

(解析)1.韻如右图,APCB為適合

條件平行四边形之一,其对角之 交真為MM之BP之中奌 (口站角互相?分),

2.THOM.08, B1 COMB=ALL

·《弦之中奌與國心联线垂直号碰A

3.DB均為定桌,故M之執踪器

以08笃直程之园(松山斜边位置大小一定到左角丁真奌之急症為以錢

边為直径之國)

($) 08 (證明)略

2以為直狸作Q园

Q. E. D.

(2)一制奌东两相交园之切线,其岳恒相等,試求其乾酥

(B‰) 0 0 '两园分拾 A,B -制是T.TC TD分别為口园 o

TC=TD.

作油))联AB 西江

延長之

2 国外部分 AQ A BP

【新々T B即上任意点

過了作00两国之切线 TC

TD

LTC TB TA

TBA TBTA

(匈周犁-2 至國作切线及到您则四色

TC2= TD2 (等量代换) 即 TC= TD

毵球上任耄贞適合條件(此马醃料性)

經設TC TD分别为00 两园

之切线且TC=TD

T8 并延長之实co’两园

That 19. the aluminium object is heavier than braša in air

分别交於E及F,則

JTC=TB-TE

TD' = TB:TEL

Therefore, fron (2)

F

B

(切线割线定理)

2.TB TE = T8 TF (代换)

TE=FF (等貴公理

EF 两真重合

TEATH RORYCLE

5但EF分别在两园上敌的生

亦重合於A奌(两周相交,至多只有两书奌)

饮T兵在AB之延長线上,即通合條件之真在軌跡上(完備性)

望日九千月一年六六九一年五十五國雞

综合以上两点 故BP及AQ為T奌之靴踏

(附註)1.因公弦 AB在两国之内,不能過其上任一点作西园之切

“线,故軌跡須除去此一部分。

2此軌跡精美两园2根軸(Rade cat Axis)

(3)两走直线ABLAC有一等腰直角三角形PQR,其舒边R之 两端,沿此两线移動求其直角頂真之軌跡.

(the) ABLAC, £rta PQR, AP=16, PQ=PR

QR两端分别在AC: AB上

(冰)當Q,R移動睡ㄗ之軌跡

(解析)1.韻如右图:APQR為其犢 動時之某一位置,則A.QPR 四奌共

B (-4CAB=LQ P R = kt. 4)

2.

AP, BIL CAP=¿ QRP=4ƒa

<时同弧国周角,又等腰直角三角形

之銳角為:45)

即下奌在2CAB 之分角线上)

但分角线 AT顯然不是乾跡,因ᅀPQR美國图形,顒A奌 太遠或太近都不能適合條件,現時得知者,祇是ㄗ之乾跡, 在AT线上,究竟其中那一线段,始為之軌跡?再討論之如下: #4 PQ- PR=a, LARQ=0. * =0°, 9√ Q£&TA§L

∴AP=QP=&

£100 PAR=45 PRA=45+0 故与APAR中,AP>PR(即AP>a,三角形中大角些对边也大 又在 ARPQ园中,QR為此國直(90°角之弦為直接 AP<QR(直為最大之弦) 即 AP<EA

·2:0=45. 則ARPQ為正方形而AP亦為直径, AP=20

(作法).作:<CAB之分角线AT.

E

AE = PQ (= a)

AD = QR (= 12a)

2 AT

3. EDP之轨迹

口

(証明)詳見解栎

(附註)).

Q. E. D.

2.當角由45漸增至900

睡 P由D移動至E

3. * APQR 213 ¶ to 7 M

示時,則之移動軌跡羊线段TS,亦奖 AC成45之角

ATE AS = &

第三次預習試題

(1)已知三角形两边及其夹角之

角线,求你此三角形

(2)A,B为直线XY 同側之两奖!

求於 X Y上 取一点,而使

LAPK= 48PYR

(3)在三角形底边上求作一奖令

興他两边距離之和笃定長

(4) 求作一直线平行於三角形之一边,而平分其间界

That is, the volume of the aluminiumy object is larger than that of the brass one.

慇的天碟

强慈危機賫

嚴患的智的

25 gm,

raaction

rupthrust

thrust

•例英文吐、

染,及同人密茨和

成長、黃交褲、西園新生考試昨放榜

生爾

邱吉爾英文書院

,翠蒸式、願、道、

淑電

一鄉、林、阿元活

基肚得世肪及夫詞質

目的:從壓,笑容

不單是在於此得到,郭聯鹊、潘惠宁、》

露値得座襬的似因,...二及正取生,下午二時舉行云。 婦女會主席,所以耶,備取生阱詩雅。摩試定於元月计五日 榮任太平紳士及中國明,於三級新生五名,

偷級備

中取生取生

由於

生微

知取赚 試文

泡剂、油鬭地、額金榮、吳萬根。

香港中文大學表示

未考慮增研究院

【特訊香港中文大奉發言人的對本葵黏者發表有關該大&

膳

群者按:中文大 李炳紀念學校 同人歡宴祝賀

李陳倩華任太平紳士 獗[@而不有”的影 ,經過一段時期後,該等新開靭谢均被證明屬究。 系」,「寡聞系」,本辙了者均岀能從可芯人女獲悉而雅作報導 空科學研究院,共二爲許啟東博士主持之自然科學研究院。此外 香池中交大學現有四個死分院,北一篇李亭做校長主持之人

人陳倩女士,殼近,爲公谋福利,所 以林監杯率價假内一日多爲社會被整務 她的勵名實保「莫之 【球學校全體隊職員,的頂畹力。她十年妙」,從這些事實來, 【本烬积会陪校上下华楣」,「但滋不倦」仰其整,推選爲主席 「初際社J九龍,宏爲她的「好行其胞因此更加捕期,没

由

得之,需要衝獗府任,由不謝娜樂,外人

The spring-balance-reada (25 - 15) gm. less.

of upthrust

版

稿昨

件晚

That is, the upthrust of water on the stopper is 10

By Archinedes! Principle, weight of water displaced 20 equal to the upthrust Weight of water displaced is 10 gm.ws and volume of water displaced (volume of stopper) is 10 cc.

Mass of.

Solution

of atopper ..

ArtVolume of stopper

- 25 cm./c.a.

main balance reads more than 52 gm.

reaction of Upthrust) gm.wt or 62 am.wh..

Ane Volume of the stopper Sh

S. G. of the stopper (hun, main balancs readi

62.80

Fonériment

To snow the pressure ac a point in aliquio increases Icash the depthod:

始时行李教资

Questions (D

A glass tube, 3 cm. in diameter, is clamped vertically over a large beaker. A flat metal plate attached by thread to spring balance is held against the lower and of the tube.

height of noter

column

J. tà) Answer une following and give a reason for your answerin

1) an joexcupe is floating Inia glass of water.ns cha

foo melts will the level of water in the glass change? 注) A box containing atr and aioind a sealed and weighed

Will the weight be different if the bird is standing: on the bottom, or flying in the airy

11) Does a body appear to be heavier or Lighter es it L

being ow22ed and Leaving the water?

Lv) in which direction would 6 person tend to rall when

Jump from a moving train anko the ground.

A piece or thetaj, masa 2 kg, and S.0. 6.8, is tied st the bottom of a basin of mercury (p0.13.6

L):Find the tension of the cora.

11) Find the ascending acceleration or

the metal as the cord is broken.

111) As the metal floats on the

surface, how much is stil Aubmerged?

(l),There's no effect on the barometer reading when the. barometer tube La slightly tapered The pressure, at

point in a liquid depends on the vertical height but -not the shape of the tube?"

An ingrense in. temperature causes the value of percury to expand and consequently. Lts density becomes amaller: Pressure at point in a liquid is measured by the product. ofits vertical" height and the weight, per unit volume: Since

be the latter becomes enaller, the barometrio heigh、 de higher with an increase in temperature

(bactors governing the pressure at any point an e-liquid

The pressure at any point in a liquid sots in all direction. The pressure old increaads with depth

3. In the liquid, pressures of points at anual depth are equal,

sure at any point in a liquid acts equally in

in a liquid la proportional to its density Ana Liquid cats normally on, contact surface.

The

:Justice

ly into the tube it starts to wever, weight of the water column adance reading-weight on metal plate lance, ceading is noted when water

The experiment is repeated for severa) spring-ms lancet

che origin is obtained LP = 4 straight line thro readings

of the water colum (pressure r drea egraph of the wel plotted are inst the neight

This shows that oresture at du point qua quid increases with. the "depth.

HB

(a) state whether the following statements are true

ar fald alving a reason for your answer:

)ff an object is moving there, muel be a resultung

force acting on it.

ji) a body which has no unbalanced force acting on

Lo does not accelerate and is therefore At rest,

(b) A piece of wood fella freely from a height of "

10 metres into water. How deep it penetrates in 117. (S.0 of wood 0.8)

(C) Abody of SIG.

or 50 at deep.

the bottom 2.

sinks from the surface of a pond. How long will it take to reách