頁四鋪張五第日六十月一十年卯乙麼夏
WAH KIU YAT PO
報日僑華
1976中學會考試題預習專欄
The instantaneous acceleration at t 11s
= slope of CD
50-0
10-15
-10 m/s2
(iv) The total distance travelled
=: area under the velocity-time
graph
堅道書院主編
物理科
(六)
何輝明
PHYSICS
(6).
(b) s
-15m
Solution for last week
I. Multiple Choice. Question
1. A is correct.
In the first case,
force
the net force acting upward on the object,
a
m.
where m is the
`mass of the objec
In the second case,
the net force exerting on the object,
(2F - W) = ma
a
2F-W
M
whej
ais:the. new acceleration:
Since '(2F-W)/2(EW);
therefore al 2a
and also a's a
2.D is correct.
Both V and Z are exposed to atm..
pressure, pressure at Vand are. equal. Both A and B are in Freet. W and Z are at the same level but
in different liquids. Pressure are unequal. C is incorrect.
X and Y are on the same level and
in the same liquid, the pressures there should be exactly equal.. Dis correct.
And E is incorrect. (Reason as
above.)
3. E is correct.
In 1s, 10kg of water is raised to a
height of 5m and pjected out with. velocity of 10ms-1
The Total work done doing so is
The Love
Win 1 sec = mgh +
(10 x 10 x 5) + x10x102
1000J
The useful power of the. engine is
$1000
t
= tsec.
1000W
Since 20% of work done is. wasted 'The power of the engine is
1000 (1-20%) = 1250W
4. A is correct:
80
Volume of the ball =
100cm
0.8
Upthrust due to oil.
Uptoin = 0.8x50 = 40gf.
Upthrust due to water.
Upt. water
/The reading of
the spring.
(balance
1x50-50gf...
( Tension. ony
the thread
-Ans
wt.of.
Total(the (upthrust ball
=(40+50) - 80
10gf
10
・(10,50)
(15,0)
(5)
(i) The instantaneous acdeleration
at t = 35
slope of AB - 0.
(ii) The instantaneous acceleration
at t = 7s =:elope of BC
50-20
10 - 4
5 m/s2
=(20)(10)+(50-20) (10−4) +
(50)(15-10) m
415m
yu=10m/s
-8--10 m/s2
= ut + at
15 = 10t + (-10)t?
106-15
(t + 1) (5t - 15) =
t=
3 or t
(neglected)
the time required for the body to reach the ground is 38.
Questions for next week.
1.(a) What are the main purposes to
use machines?
(b) State 'the function of a fixed pulley and that of a movable pulley.
(c) The followings are two methods off pulling a heavy load up an in- clined plane which is inclined at 30° to the horizontal.
Which one will you choose? State the reason for your choice.
LEAD
METHOD {5}
LOAD
30°
METHOD. (E).
(d) What is the velocity ratio of the inclined plane of the above applications?
(e) What is the total velocity ratio if
(i) method (I) is used; and if (ii) method (II) is used? (f) If the efficiency in both methods is 80%, calculate the mechanical advantage in each case. 2. When a piece of copper of mass
400g is hung on a spring of length. 50cm originally, the length of the spring increase to 54cm.
When the suspended piece of copper is totally immersed in water of density 1g/c.c., the length of the Spring becomes 53.5cm.
(i) Calculate the weight of that.
piece of copper in water... (ii) What is the upthrust exerted- on copper when it is totally immersed in water?
(iii) What is the weight of water:
chaving the same volume as that
of the copper?
(iv) Calculate the specific gravity
of copper..
If the suspended piece of copper is now totally submer~
density 0.8, determine
ged in paraffin of relative
佳!
四期
日八十月二十年五七九一层公年四十六國民輩中
(v) the upthrust experienced by
copper in paraffin;
(vi) the weight of that piece of copper in paraffin, and
(vii) the new length of the spring.
有教僑華
4A:(1) Ferrous sulfate is: oxidized
by potassium permanganate to form ferric sulfate.
(aq)
Fe(aq)
The presence of ferric ions in solution is responsible for the color of the solution.
Potassium permanganate acts as an oxidizing agent and is itself re- duced, therefore it loses its pur- ple color.
8Htag) thioa
Mri
+2.
(purple)
+
(aq) (colorless)
5e
(ii) An insoluble hydroxide is formed.
Fe+3
e (aq)
+
Fe(OH)
3(5)
ferric hyd ro xide
1976中學會考試題預習專欄
堅道書院主編
30H(aq)
化學科
(六) 李國榮
B. Element
relative number of atoms.
26.67
12:
2.22
2.222.22
11
4.44
CH:O 11:2
CHEMISTRY:
Ariswers to Question (3) & (4) 3A. (1) Sulfur dioxide reacts with
oxygen 'in the presence of. platinum as a catalyst:
250
2 (8)
sulfur
280.
3(g)
sulfur trioxide
dioxide (ii) Sulfur trioxide dissolves in the acid solution to form 100%. sulfuric acid, and then more of the gas would react with the acid:
: 50
+ H:$804(L)
03(g)
sulfur trioxide
oleum
The product is a fuming liquid.. B.(i) The choice is sodium chloride. (NaC1.), sinne glucose (C-HOg) gives a covalent solution which does not conduct electricity. Copper (IT) sulfate is a blus
cry- stal which decomposes readily on heating.
(ii) When sodium chloride (NaCl) "dissolves in water, the solution is cionic, therefore it behaves as an electrolyte. Due to the strength: of its ionic bonds the solid has a very high melting point (8080).. When it is in molten state; mobile ions are present, therefore it is. again an electrolyte. In the solid state the ions are non-mobile, (only -vibrations are possible) thus it
does not conduct electricity.
C. According to the equation
CO2 + H2O + K,CO → molecular weight of K_Co., =2(39) +12 + 3(16) 738
The amount of KCO in solution
gm mole
The amount of KHCO formed
3
.50
(2)(138) gm mole molecular weight of KHCO3
39+1+12 + 48.
Weight of KHCO
#.100
The weight of KHO
138m mole
(C) (100)
138
36.23 gm.
·precipitat-
14.23 8.
3
ed = (36.23 - 220)gm
D. Very pure sulfur can be obtained by heating the sulfur to its boil−:
ing: point, and then collect its th
sublimate on a lcean cold surface.
Empirical formula = CHO molecular weight 12 + 1
Molecular formula
02F204
32.45
(CH2)
The compound is oxalic acid
According to the equation.
+ H2S04
→ CD + CO→ + H2O + H2SO4
COOH
Only carbon monoxide is left after the treatment with potassium hydro- xide.
Mole of carbon monoxide formed.
Its volume = (22.4)(4) (300) (750)
liters 2.49 liters
The solid was copper (II) sulfate pentahydrate. CuSO-5H-0
4 (i) When it was heated water of
crystalization was lost, the blue crystal turned into a white powder. Water escaped as steam which may condense on any cold surface.
Cuso
CuSO
4*5H2(s)
(3)+5H29) (ii) Further heating would produce
copper (II) oxide and sulfur triu oxide. The gas was acidic.
Cuso
+ SO.
4(s)
Cuo (s)
black
3(g)
colorless
(iii) When sulfuric acid was added to copper (II) oxide, copper. sulfate solution was formed.
"CuSO4 + H2O
CuO(日) + H2SO47
4(l) in solution
(iv) On evaporation copper (II)
sulfate pentahydrate was obtained
教
DPA
二:偉文( 塞〔窈缾校友會慈云山、七H座,電話, 中意點:一:碑慧
大 教三三〇號
學校
八五三三四二
.
|潍仁下午校》;三會
聖誕卡圖案設計比賽
參加作品水準頗高
蟬〔张强小案)。
禮(官灣官立上)
·親會學校,李明 二:招鬘催灬司徒氏宗
幼章:心:民
|体雄入官地利亚女
館展出 爲期兩個 評定 今日起分別在各市政局圖書 作品約四千五百幀 成精經告
(BEREC) -11)
創風格,水準頗高,評 幀。其設計及結構別 多間,作品約四千五百 新法)。 比賽,現已經灣完學。」二...分婉兒(呑浓新法等(培正中學)·· 本磴添加之學校共四臣),三;李俐光《香米、李淑賢(溥仁學校), 下攤術館及市政事務芹;尹雅王C鶴山小學》:ADA CHANY ㄦ雅小事》, 胡感觸 【雀訊)市政局淋一尹滋補荫山小學,三糠蠣宀培正中學】三:薇立升(趙公苷紀念
·麥好金〔美基學校
巾
.
名十金學助東大
生學院學工理頒
(金礒助獎須生學校族示業查詢:
多書數爲者助資
:一:陳
荃灣甯中), 李世 ,三:張燕玲〔荃灣官 北〔蛮公會主恩小學)
中潑組:一:何仁樓(
「周德經
之·昨
幼乘緄:一:吳輝 香発仔圓舘:
列之標準以創作爲主輝(香港仔宫小下午)
幼童組:一:志 石鬮書館:
嫔(全第三下午校)
· 幼童報:一;梁運|十個六農隈報局助學金
與該校季生。
日下午在工學院骐
,手法爲次。所有參加.,二·染摆鞫《羅宗淦光、保良局聯誼會丁未
同同下光
同上。
中祖:鄧要桃(
歡迎各家長及小朋发冷」。 得獎者將獲通知有關雅、 張安平(聖伯多殛下午 八)日起- 俏期雨戎a. 鴨洲坊產校),二..」獲得大東體報局助學金之十名理工學院學生合照」七千五百萬元之新水星 各市政局闊季雅城出, 光í羅宗淦紀念小學) 同上),三...梁儆張八校)、三:鄒秀容(登】每個一千示,於一九廿 |比賽之酿誕卡,分別、紀念小),三:許志下午校)、二寶(英賢率大東電報局助學金 完第三下午校 ) 大東電報局副總經理之一排中間與一念於灣仔布傍耗資 大度黨成,助學金中五
1 年1月首次頒發,以
「獎儀式之日期及地點。 》,三:張文亮〔鞭伯
儷雅興權予淤,兩個 與工商管理系,而後
俺辟者名單如下a
恭燕上华。
大童常陈出舘 中磁綎:一:孔德 | 李琦〔仉爱下午校》 一、i:健湊洋〔番禺
心( 番禺路)→二:
「
幼綎..一..超妙!。
},{┅质疑C茧愛 校下午,三·費者關
〔洪氏宗親會被上午 [欧術官小上午)
幼童衪..一:王
- (53··RKEKESIDENCE ®).
-跛爾獎學金发幸運,仍盼各同學函禮爭取
,既可保護牙齒,復可參加獎季運動,一舉兩得
一元,則已另函道知領獎。
·弟姊妹羡慕不已。各中獎者或表示君牙膏. 燕客出一份參加表格,包獲中二獎,令十一位兄 獎學金一千元,尼付五年學費。住在元朗的賴多 中三獎,可謂三喜臨門。十二張的吳仲驗同學,金博 一堆同學,除自己獲中頭獎外,兩位弟妹亦分別獲 童小 「學金五百元。至於四百名三獎,各得獎金一百 獎五名,各得獎學金」千元,二獎十名,各得獎 , 五位頭獎得主之一的兼课程同學表示,現獲 兒
露深棕欖(香蓓)有限公司舉行。到塲你獎之 獎學金頒發儀式,於上月廿四日想巾匹太于行高 (鍌訊 高蹉潔獎學運需經告結束,五萬元
該公司鰌經理戴伟時於頒獎時勉勵各中獎同交
高露潔獎學運動 數百人獲獎學金
玢]香港新汰 》,二...(溥仁學校)、11·林
薄扶林公立爾啡館、小學上午)。 中學),李安(聖貞:[招杌〔卜維廉中學 11. EZ (KE $(HS) - il
·幼童組:一:莫掸 高打老道两米館:
三:江志文 何福黨
【小
誌雜文圖智签童兒
「刊月半」改士博小
多者開訂校學味趣於育教鴦
求小近選集於學童稱許次以一一智的發出出
串,篩 訂這介校酞臟,育來,小雞兒青服版~
讀,月特渚續該關爲額均迎,家界確出磚誌童價是公室一
內刊自愛戀刊。兇,樂·兒長推受瓶士| 整個實用心機
人。
材等開文爲一百七十 容費+書籍及其他器 ,每月平均因交通費, 每一名理工學院的生 入低於一百八十元,而
·費開支如租及學棄祥
,家庭分予平均每月收
•其家庭於減去日常
一握,劉席維及陽時各十
:約三分一之理工學生
生福利鯧今年盘 據理工學生會及學
視黑,難裕·麥教
——今年獲獎事 撒、林聯邦,吳怏强,
杭季斯各一名。 美脚淸-李志,紙志
體流浪,多"電流系及
學
世事金七十一個,表近湛
助學金共五十九佰值 過一項潺商後,再獲
月紅 關三年一次之各國代表,莊時亦敦代香治教師 在方文莊代表前往參加 阿妈祖爲望大雲-特推聚會總會出。 學稱號,兒定十日起,一連主題外,並將對論高 童麼經,一天在意大利佛羅斯召教師任務等開闊,方文
̇中,家以前際自由教師工會|扮演的角色」作爲研究
(港)信红酶的地址出朮程一ㄧ1千六百元。八茜)
教師會轉秘書方文燕代表争加
·昨舉行代表大會
國際自由教師會
加秘:
「加以革新;撼爲輕鬆倪| 大會 - 除以「在轉過一晚午夜出發。〔〕
客木技小老貼紙,其首都安哥拉,葉行| 方文燕巳於前(十五 」,每册只饼一,內廿四日, 將聚集於土耳港,前日特設狂歡。 第九期起改爲「半月刊| 五各國代表由廿一日至月之工會訓練證耳 求,特自代表大會完畢後,以色列,參加爲期四低 國際自由致師工會|官校祗主席高錦超前往 以方氏遠行,並值讓書
·敦師會理事曹国人
· R. 羽傳;小博士說
機沒人來了5小小傳奇 一的妙計;生活幻想故事 記;其季故事·强奶媽 故事-潛水艇海崴遇
·百發百中科學驚險 事:半邊海;生活故事 一字和「囚」字,童話故 【中國兒童故事:「園」 一日出版,要目計有 !第九期日於本月十
快 - 從而調劑心智發展
」:「小图質膦」的兒
此外,尚有一小塊文章 粗話和重整等十餘舊。
輕聖誕咭,及腦筋,
童作品。
繡酸可曲,家長倖于女
有代售 - 歡迎學校學生
·做刊各大書報對
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