頁二第張六第
日三廿月十年申戊歷夏
WAH KIU YAT PO
報日橋
四期星 ®
日二十月二十年八六九一展公年七十五國民華中
育教僑華
【已知)OP两国交栏AB
上文中學會考試題預習
物理科
(六)
PHYSICS (6)
陸永熾R
(2) Lever The lever is the simplest example of
machine which enables a smell forse to overcome
が
A large wight or reaistance. It works with, the
hindiple of moments, Thus, the principle is sometimes known as the law of lever, which states
that sum of the moment cause by the load is equal to that by the effort. The moments of Imad and *ffort are, therefore, in opposite dimention. Ir one is in clockwise, the other in in anticlockwise.
load er effort arm
1st ORDER Load and Effort. on opposite side of the Fulcrum
2nd: CHDH
Load and Liffort On the same aide. of the fulcrum: M. A, la alwayg greater than unity
3rd:CRUSH
· Load" and - Effort"
on the same side
of the fulcrum.
M.A. is alwaga
Jess tian unitv.
5一九六九年中文中学考試預U
數學科 (六)
番仲强•
第五次預習題解答
(1)求作一团,切一己知园柊呼詔奌,且些一下知直线相切
(已知) ○团及其上T AB為0园外一直线
(求作)一园典0园切於T且牌AB相切 (作)1.联OT
2.1874 CT 107
3 ABCE
3作LBCT 的平
分钱OT的
延线P奌
4 UP, BJ PJ
為半径作园
只作LACT的
6.以P為园心PT為半接作园
(明)!
QE.F.
(作访上)),作。因直往 CC,
垂直於AB
CT並延長舆
酸OT並两端延長
A
5.以為园心,PD半作园,
不過工作AB的垂线交TO延线於英
6.联TC,並延長一交ABD奌
是以 為心PR為半作园 只PP两园的為聘求
(求作)遇A奌作一直线
各书O.P两园於CB
D而令CA=2AD (作法一)1.樓OP
2在OP上取E奌使
TA
ILD A 14 5A 15 CAD
即好!®
定理證明不赞
1. PA盞延長!
EPA AP=2PA
以為心的為 半種作园园 茶奌
三联CA並延長之
CAD$
用「佳似法
中国文传似中心
為A吴其位似比為
(5) AXOBA 04 £ #13 A 14=☀ BOTA PA➡ RAC
(乃知)A笃0国内已知点
(求作)遇A作口园之BC
ABA=EAC
(作法)).联OA并延長。
SP 12 APOA
2.以P茑园心.0周半程
的士為半狉作用友团
Q. E. F
* C, BC.
3TY C.A.
柊BBA各延長之交
则DC, 及 BC, 均為好求
Crowbar.
vineell
(已知)0园,直线AB 及其上下要
(求作)-园與AB 切于
丁卖且與0园相切
(作法-))遇T奖作
2直线垂直于 AB
2.在L上者 TC=TC:
=○园半程
4.以P為心,PT為半作园
5.联並作其中垂线交兒拎R奌
6. 以為心, PT為半往作园 7 P+?两园均為巧 (証明)略
(明)1期PC,並遇作其行线典CA之
Bi
延线支於D則 AAPC. LS & AOD 【△底边平行线)
AP PC
==(相似形对这成比例作诗)
30D= 2Pc;一口因半程(等量公理,作法)
4 D奌在0园周上(-奌奖园心距離等於半必在日上一
但因D在CA延线上D桌重合於B(因B為C.B.典国交套)
6 CA
BA (***) BY BA=2AC
同理可証AU RAC.
QE. F
(例)銳角△ABC中,凡為其外桂园半,試託2
(証法一)設如右图联OBOC 則
LA= = eBoc (园周角等於对同弧
同じ角之木)
The bus begins to topple if it's tilted 30° The is then just above the point of turning 01 h is the height of C.G. (In fig. a)
1.225 cot 30: 2.12 m
If it is tilted 459. The ensin on the top 19 taken away). The weight | of the bus terda to turn the bus clockwise
A sin(459-300)
The force, F, acting at G.G, tends to keep the bug in equilibrium by offering a moment
3003
- xain15°
tan150
8000 (tan15°
2143 kg.
Ang (1) The centre of gravity of the bus is
2.12:metres above the base.
(11) The horizontal force acting at G.G. 13
2143 kg.wo
LOW (a) (1) Conditions of Equilibrium of three for
(1) Tas ir lines of action are concurrent. (2) Satisfy the law of triangle of forces
If three forena acting at a point - maintain it in equilibrium, then any triangle with its three sides drawn parallel to the direction of the forces has the length of its sides: proportional: to the forces,
(i) Condition of Equilibrium for three parallel
Torceste
(1) The sum of forces in one direction is
equsi to the sum of forces in onposits direction.
(2) The sum of anti-clockwise moments is
equal to the sum of clockwise momente. (b)To verify the Triangle of Forces Law.
A piece of paper is pinned to amerected drawing board. Three pieces of thread, each about 20 cm. long are knotted together. :securely at a common point 0. The other rree
ends are attached to the three waight-hungers two of which passes through two pulleys plamped at a suitable position..
(10=) 1.400111 CC, LAB.
2遏T作LLAB
3.联 CT交0园於卫兵 4.联OD並延長之交见栓供 5.以P為心 RT為半径
̇作园
6.仿3至5.方法:作
·P两园均為求
DE F
(3)求作一园如一己知园於兩設奌,且興另一己知园相切
(作法)聘 PT至延長之
(已知)OP两园「為P园
((作)一园奖0圆相切. 且切P园於T奌
2. 在PT上截 TATAL O园半程、
3.联 OA,并作其中垂线典TP延线支於Q 4.以Q為心,QT為半经作园
5.以A,代替A,仿(3)(4)方法作园.
《証明)從略
Q, E.F (4)O.P两园友於ABA作一直线,與口园交於C黑
PE交于DA令 CA=2AD.
【等腰△底边上之高,书写角及底边
BD "son 2 BOD=- 即 unA=亮一款R=
(証法)作直径 80D,又联 CD, 則
£D=cA(利同弧园周角相等
B®
8 < BCD=st < (‡QQ8A$1A) 在ABCD中
BC
D ==
BD
A
BR
第六次預習題
(各計算題,答案準確至三位有效數字)
在塔前50呎處,測淂塔頂之仰角為4元又测得
塔頂上之旗竿頂,其仰角為54求方旗竿之長
(2)两园丰祆各為7吋,8吋,园心距離口味求两园之ㄨˋ
角(即由交奌各作两园之切线形成之角)
(3) 詔 △ABC中,其各角正弦之比為 2
dinB 及 sin C 之值(用根式表示之)
(4)設园過△ABC的顶奌A而切BC边於C臭試試
(5)在 42呎高之屋頂上,測得一塔頂之仰角爲: 14° 13.若
在此屋之下面测之,則仰角鸟 23"19 求塔高
6)在一塔之正東:A奌,測得塔顶之仰角总31”,在塔 之南偏東:41 B測之,則仰角為25設塔高200呎
求AB距離
7)在475呎高2崖上C奌洲地面上两奌A及B 其 府角分别篇 10° 32及14°54<ACB=56°13 求
AB 距離3
3)設如右图:0园為單位国
日為第二象限角試証
(a) tene
(@).com
Aim A
(未完轉入第六張第三頁)