CHAN'
<-BAISERER KRAF 30,
WAH KIU YAT PO
B
# # 15 W
英文中學預켭
1968
物理科 (十八)
(11) An closed pipe,
4
·陸永熾·
3). Solution
Physics (18)
(a) The frequency of vibration of a stretched
string under constant tension is inversely
proportional to its length, in **
}
For a given length of string the frequency of vibration is proportional to the square root of the tension. In XT)
N
(b)
Freq. of fork (n) c.p.9.
256
320 382 512
Tension of wire (7) gm.wt.
Square root of tension *ff (gm.wt.)
1600
2500 3600 16400
40
50.
60
From the graph, we obtained that T
- 75.0 ľ. 5625.
The tension is, therefore, 5625 gm. ut,
a) Since frequency tension, and
frequency ∞
Longth
if tension is kept constant 300000
100
√2
-
600
08
1
600 x
new length
new length 300
The new length will be 10 cm.
if the tension increases to 8 kg.wt, while
the length is kept constant, then
300
new frequency » √ễ
new frog. B
300
The frequency should be 600 per sec,
34 Solution
(*) Resonance
"Resonance, 10
2
phenomenon occurs when- aver particular body (or system) vibrates (Oscilistes) at its own natural frequency as
a result of receiving impulses of waves from some other system which is vibrating with the same frequency.
(b) (1) An open pipe
X
The distance between the 1st and 2nd resonance
positions i# A - 4 = 4
28FEB 1968
The distance between the first) two resonance positions is à
(a) To determine the velocity of sound in cir
room temperature using é closed resora {{C® tube.
The tuning fork of known frequency 15 ME just above A as shown in diagram. The Lude gradually raised so ay to increase the length of the air column k until the sound emitted Dy the vibrating column of air is at ite maximum Loudneay, making slight adjustment'
until this resofce is most marked (L).
A second resonance je again performed by further increase of the length of wir column í Ls d
Sinc# X..
where E is the
first
021
lenge of air column for the
resorahCE
is the length of air column for the second resonance
o is the end-correction
A is the wave-length
A
a is the frequency of vibration.)
By subtraction (eliminating o)
三
日八廿月二年八六九一楼公年七十五國民航中
1968中文中學會考試題預習專欄
英文科(十八) ·何玉柱 •
JXV111
Answers to Exercise XV.J
[1. Comprehension:
}
1) Thomas Moore was a famous 19th century
Irish poet.
2) When Moore came back from the business
trip, the bad news that his wife had įcontracted smallpox awaited him (Be
careful not to say that the family doctor awaited him as the question is "what?” not "who?"
3) If one gets smallpox, usually one'a akin
will be scarred and pocked.
4) Moore's wife didn't want to see him be- ' cause she had seen her own face in the mirror and did not want to let her husband see her with such an ugly face
she did not want to spoil the pretty impression she had had in her husband's heart.
5) No, Moore had never written any song before)
the one he wrote for his wife.
5) Moore's song which ensured her of his love.
to her made her draw open the shuttera.
7) In his song, Mooresaid no matter what
happened to her appearence, he still loved
her.
8) a. favorite: most loved
b, flawless; fair, without defects.
◊. hesitated: could not decide what to do.
d. swayed: moved
sat up most of the night: did not go
to bed but work for the greater part of the night.
f. groping: feeling the way.
2. Suggested translations:
KONG PUBLIC LIBR
L1) - A
2
(c) Velocity of sound in air 330 m/sec.
Distance between the surfaces of the water for the first two resonances is 27.5 cm.
... ( l, - l2)
A
2.
- 27.5 cm.
wavelength, A *. (2 x 27.5) am.
frequency, n-
velocity of sound
wavelength
330 x 100 2 x 27.5
• 600
Ana. The frequency of the fork is 600 c.Þ.B.
Questions ror next week
35. (a) Explain what is meant by magnetic field and by
magnetic induction.
(b) If you are provided with bara of iron and
steel of the same dimensions, and any other necessary apparatus, how would you demenstrate the main differences in the magnetic properties of iron and steal?
State these differences and indicate, giving reasons, which of these metals you would use for (1) a compass needle (11) the core of an electromagnet
(c) Describe an experiment to demonstrate that &
electric current has a magnetic field and atate a rule which connects the direction or the current with that of the field. 36. (a) Define magnetic declination and dip.
(b) Dascribe how you would obtain the valus at i
given place of the declination and dip.
1)我最喜歡的愛情故事是一個真實的事蹟。湯 馬士摩亞是一位著名的十九世紀愛蘭詩人。 他結婚後不久就因公外出。等他公静定 平國家時,在門口迎接他的不是他那位 美廈的新婚夫人,而是他們的象速醫生。 「你的妻子在樓上,」醫生說:「但是她要 求你不要上去,然後摩亞才知道了可怕的 真期:他的妻子染上了天花。這使他 一度無瑕的皮膚疾痕斑駁。她曾在鏡裡 望了一眼自己的影像,以後就下令把所 有窗簾拉緊,而且要她的丈夫永不再見到 她的面
- 摩亞不肯听這話,他跑上樓一把拉間他
夫人的房門。房中黑如夜。黑暗中寂静
無聲。摩亞扶着將走過去,摸索着煤氣灯的開闊。
1) When people who first learn to take
pictures have the interest and the motive to start the study of photo- graphy, naturally they will want to have a camera. Then they will have to consider the problem of the choice of cameras. Many beginners will ask what brand of camera is the best. How- ever, in fact brand isn't the only important thing. When we buy cameras, there are several details which deserve our careful_considerations. Prepositions
There is no definite rule for the use propositions which are very many in the English language. If we want to use pre= positions correctly, we must pay close" attention to the correct uses of them and ́ learn them by observation and practice. Her I can only point out some most frequently used prepositions.
AT, IN
They may refer to time and place. When "at" refers to time, it is used with a shorter. period of time (compared with "IN")
I went there at five o'clock (a" de- finite point of time) in the evening (a pericu of time).
Here are some phrases to be learnt by heart Et noon, at midnight, at the beginning (end)
of the day (month, etc.), at that time, at present, at this time of the year, at his age, 1 at five (minuter) past eight (o'clock) in a moment, in a short (long) time, in an hour, in the morning (afternoon, etc.), in January (Febrhry, etc.) in summer, in the daytime, in this week, in the past, in future, in the near future, in the twentieth century, in youth, ir the long run.
When they refer to place, "At" referé to s smaller plice while "In" refers to a bigger one and "In" aldo implies the sense of being inside
a limit.
2. E. She was brought up at a smell village
.n the country.
at the end of the street, at the top of the lass, at home, at the foot of the hill gat able (seating), at desk (-working), at. school (=being a student), at the seaside, at :he side-show in the fair, in the sky (ale), in the water, in the dark, in the middle of the street, in the light, in bed, in a theatre,
There are some other well-established phrases with AT and IN:
at the sight of, at the sound of, at ease (com- fortable) at work (working), at hand, at war etc. in sight, in health, in peace, in (or on) behalf, of, in consequence of, in honour of, in respect of, in spite of, in the face of, in regard..to. in love, in turn, etc.
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