1970-03-04 — Page 22

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10英文中學會考試題預習專欄

堅道英文書院主編

報日僑華

Coefficient of volume expn. of glasa

-6

= 24 x 10 per deg. C

Coefficient of apparent expn. of paraffin

(9. 0.24) 10 4.

三期星日四月三年〇七九一層公年九十五國民華中 育教僑華

per deg.C Assuming the mase of paraffin left in the vessel be M gn. the mass of paraffin expelled will be. (40 M).

Since the apparent coefficient of expn. of par- affin

mass of paraffin expelled muse left x temperature rise

(40 - M)

\(M) XC70 )

九七年感

中學入學試試題預習專欄

英文科

ere to

SECTION. A ·2·

II

SECTION B III

智慧出版社主編

(十八)

Previous Exercisee

1.8 2.D 3.2. 4.A $510

2.5. 3.Q 4.R

5.1

1. My hobby is collecting stamps.

There was a cerriage waiting for

us at the station.

3. Instead of drinking wine he drank

a cup of tea,

Children find pleasure in playing

in the rain::

Travel on the sea was not a very

difficult problem.

popular, iuportent,

(40 -

*

(9 - 0,24)10 x 70%.

物理科

(十八)

PHYSICS (18)

Solutions for Exercises 17

17-1.

c,c. of the liquid at 0°C 1 13.596 gm.

is the coefficient of expansion of the liquid 1oc. of the liquid at 0°C exjande to (1 + t) c.c. at tc.

Therefore if d is the density at 0°C and d, the density at t

-8.76 x 70 x 10 x M

010613M

1.0613M

40

1.0613

37.7 m

Answer: At 70°C the vessel holde 37.74 gm.

paraffin

Coefficient of exon, (cubical) of glass

-0.000024 per deg.C

Capacity of the S.G. bottle at 20°c

50(1+0.000024 x 20) 0.0) Density of glycerine at 0 g -1.26 Em per Density of glycerine at 20 C=α, 20

ition

Therefore for mercury t

The density of it at 60°C a.

13.596(1 - 60 x 0,000182)

13.596(1) 0.01092)

13.596: 0.149

13.447 g per c.oi

answer he density of mercury at.

13.447 m per cic.

Coefficient of linear expansion ofglans

0.000908 per deg. 0.

ia

Coeffiolent of cubical expansion of mercury

0.00018 per deg, 0.

The mass of mercury in the tube is equal to th product of volume and the density,

At. 10°C

·MADA: «.

At 30°C.

10

3030

and since the mass ie constant

10 x 410 3030

The volume is the product of the length of column - and the cross-sectional area of the tube, so

whonce

10

='50

10

€30*

210

130. 50 x

#30

The change in area involves the coefficient of super- ficial expansion of glass, which is twice the coeffio- ient of linear expansion. Therefore,

also

erér

1011 + 20x 2 x 0.000008)

1.00032

£10 £30(1 + 20 x 0.00018)

1.0036.

50 x

X 430

50

1.0036 1,00032.

1420010

where is the coef.

glycerine

real expn.

1.26

1 + 20 x 5.2x10

Mass of glycerine at 20°0 is equal to the product of volume and density at the same temperature.

Mace。。 = 50(1 + 20 x 24 x 10-

126 x 10

+20 x 0.00052

50.024 x 126/101.04

62.4 em

Answer! The bottle contains 62.4 en of glycerine,

ansion of Gapes

In the case of gases both volume and pressure change

- with temperature, If the temperature is kept constant:

PV constant

That is, the pressure of a viven made or gas at conat- ant temperature is inversely proportional to the volume of the gas

This is known as the Boyle's Law.

If the pressure is kept constant: (Charles' Law)

where 8 has the value of

and is known as the volume coef. of a gas,

273

or 0,0036 per

The volume coefficient of a gas may be defined as: the increase in volume of unit volume of the gas at

0 degree C when it is heated to 1 degree C, the pres aura being kept constant throughout.

If the volume is kept constants (Pressure Law)

(1 +77%)

where is the pressure-temperature coefficiant,

and has the same value of 3, namely 0.0036.

The value

273°C.

273

suggests that at the temperature

C. the volume and the pressure of a ram vanish, and that -273 0 is the absolute zero,

The Absolute Temperature Scale

The absolute zero, -273-0, suggests as absolute scale of temperatures on which the freezing point of water is +273 K and the boiling point of water is +373 K. Absolute temperature is designated as degree K in honour of Lord Kelvin. Thus,

r = c + 273, or THE+ 460

Charles! Law and Pressure Law may also be defined in terms of absolute tepperatures:

Charles's Law

Provided the pressure of a fixed mass or gue is kept constant, the volume is directly proport ional to the absolute temperature, i.e.

50 x 1.0036(1 -0.00032)

50 x (1.0036 -0,00032). 50.164.

Answers At 30°C the length of the mercury columa

16 50.16 cm..

for approximation

Comfficient of volume expn. of paraffin

per deg.

where V ie the volume and T is the absolute temperature.

Pressure Lase

Provided the volume of a fixed mass of gas is kept constant, the pressure is directly porportional to the absolute temperature, ±‚ë.

where P and are the pressure and absolute temperature respectively.

poor, old,

them,

cheering,

aide, team

exercise, eki

favourite

SECTION

Read this carefully:

Christmas is a time of joy and

appiness. People forget sadness and try to show kindness to everyone. Children look forward to Christmas for many weeks. The warmth and friendship of Christmas help us to forget the darkness and pold of winter.

When the children wake up on Christmas morning their presents will be beside their beds and

they will think that Father Christmas has brought them. During the morning, Mrs. Johnson and

Jenny will cook the Christmas dinner. Mr. Johnson, David and the children will go to church. The church is always very crowded on Christmas morning, For Christmas dinner they will have turkey and pudding. In the afternoon they see and hear the Governor on television; then the older people will rest while the children play games,

General Gas Law

(未完棘入第六張第三頁)

Combining the volume-temperature. relation, the p pressure-temperature relation, and the Boyle's Law of pressure-volume, the general gas law is obtained. It takes the forms

where P is the pressure of the gas, Tie the volume, and T is the absolute temperature of

Exsuple 18-1

How deep is a pond if bubbles forming at the bot-l tom quadruple their size in rising to the ton, and if the temperature at the bottom is assumed as 10°C, and the temperature at the surface is observed to be 20 deg C?

Solution

Applying the general gaa law, where the pres eure at the top is atmospherio pressure B and the pres hure at the bottom exceeds atmospheric by an amount corresponding to the given depth of water. All temp eratures must be expressed on the absolute scale.,

where P-1 atm.

42

20+

273

-10

Therefore,

(1) (472)

The pressure due 2.87 x 34 ft of water.

to 37.6 ft of water.

283

293

3.87 atm.

to water is (3.87 - 1) atm. or

That is 2.87 atm. is equivalent

Answer: The depth of the pond is 97.6 ft.

Exercise 18

18-1. The volume coefficient of a gae is 1/273 ver

O calculate the volume coefficient per

18-3..

18-4.

deg F. What is the absolute zero is dex.c and deg.F?

The density of air is 1.29 gm per litre at N. .P. Calculate the gas constant or air for a mass of (1) 1 gram, (11) 10. grams. That mass of air has a volume of 850 c.. at 27 deg. C and 75 on mercury pressure?

A barometer tube 90 ca long contains some air above the mercury. The reading is 74.5 cm when the true pressure is 76 cm and the temperature 15 deg.0. If the reading is observed to be 75.8 cm on a day when the temperature is 5 deg. C., what is the true pressure?

A peiton vi

effective volume 200 och 18 used to exhaust a vessel of volume one litre. How many complete strokes will be required to reduced the pressure of the air in the vessel to one-hundredth of its initial value?) Assuming that the temperature remains come we