夏二第張七第日八初月二年未己歴夏
1979
報日僑華
二期星
the electron
日六月三年九七九一圈公年八十六國民華中有教備華
/BAC-90” and /CAD=30o.
中學會考試題預習專欄
(charge of the electron)
(potential differe
物
(#=)
Calculate the length of the
diagonal HD on the nap
The scale of the map is.
such that the length of the
side of the field
represented by AB is 420m. Calculate
(a) the area, în sq.m. of
the
field.
(b) the length, in metres,
of the side of a square field of equal area
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PHYSICS (22)
Corrections to Physics(21)
Two parallel metal plates
and Q, 10 un apart, are connected to the opposite terminals of a 200 volt power supply as shown in
figure 1.
➡ (1,6x10-*°)x(200)
3.2x10-17J (Ans)
Let the maximun velocity of the electron be ❤ ma
The electron will acquire riaximum velocity if all the
potential energy gained in converted into kinetic energy.
Zmv" - 3.2×10-
|(9.1x10−31)(v2)
- 3.2x10”
7.033x1013
- 8.386x10
The current through A is
the sum of currents through
B and C, therefore
power dissipated by
R
powe
(Ans)
(c) The distance between
the plates 10 mm
10 TEM
power dissipated by
B and C have the same
brightness and A is
the brightest.
Acceleration=
(8.386x107) 2(10TM2).
3.(a)
17
35x10
ΖΩ
21.0
the diameter ADB of the
circle ABC is produced to
meet the tangent CD at the point D. IF ZADC-36o. Calculate DAC. (Geometry theorem need not be quoted when used.)
A man left
— of his money to his wife and half the remainder to his son, The rest was divided equally Amongst his five daughters, Find what fraction of the money each daughter received.
5. By selling an article for
$18 a shopkeeper makes a profit of 44% on the cost price, at what price must it be sold in order to make a profit of 40%?
12
Poles AB, CD onch
the frame work of
tent consists of two
of length 1.8m, connected. by a horizontal pole BC of length 2,2. The framework is held in position bý four equal ropes AP, BS, four CQ, CR with their lower
a rectangle PQRS on the same horizontal
plane as A and B, ON
that PQ-3m and QR=1. Calculate
(a) the length of AP.
(b) the inclination of each
of the rope to the horizontal.
(c) the length of each rope.
13. In the figure,
Figure 1
The charge of an elect- ron is -1.6 x 10-19¢ and
the mass of an electron
2,1 x 1073 kg
(a) If an electron leaves
the
negative plate, how much energy will it gain when it reaches the positive plate Q ?
(b) What will be the naxi
mum speed of the elect-
ron if it leaves the negative plate with negligible speed ?
(c) What is the force on
the electron when it is
in the the electric
field between the two
plates ?
(d) If a magnetic field is
12
3.
applied as shown in figure 2
Figure
2001
G
210
(b) The key K is now closed
and it is found that
the value of R must be changed by 21 in order to restore balance. Should be increased or decreased ?
Suggested solutions to Ex. 11
1.(a) The energy gained by
the electron
(9.1x10 (3.506 x101
3,2 x 10(Ans)
(d) The electron will be
deflected downwards,
2.(a)(1)
the resistance
bulb be RL,
When ki and ky are open,
the current is 0,3 AN
When
p.d, across E, F * (0.3)(u)
is closed,
the effective resistance
2R
current through-
0.6A (Ans)
(ii) When k ̧ and k2 are hoth
closed, the effective
resistance
$
The current through A
0.3R
R
0.94 (Ans)
An shown in the figure,
ince the resistance of
Bis equal to that of C, therefore, the current through Vis aqual to
the current through C.
When k is open,
7 21
(202. (Ans)
If k is closed, the
resistance of the branch
AÐ is decreased, hence, the value of R should
he increased,
(c) Effective resistance
of AB -
56x 21+3x
(Ans)
Let the number of alpha and beta particles emitted be
and y respectively
238
92
230 90
238 - 230+4x
** 2 (Ans)
90+2x-y 90+2(2)-y
94-y
-2
(Ane)
two alpha particles and
two beta particles are
emitted,
數學
RADIO ELI KILANESE ELMAIS
Mathematics (22)
Exercise 10°-
Answer "ALL questions in Section A and any SIX questions in Section 8. Section Aï
1. Make k, the subject of
the formula d
A regular pentagon inscribed in a circle ban each of its five sides 20cm in length. Calculate the radius of the -circle,
3. In the figure,
the
The diagram shows t internal circular cross- section of a proposed channel tunnel. The total width of the horizontal
road AB is om and the maximum height CD of the tunnel is 7.5m. Calculate the internal radius of the cross section.
7. Simplify.
{1 tanx).
(1+catz)
+ (1+ tanx) (1 cotx)
Solve the simultaneous
equations;
x-2y
xy- y = 8
Section B.
6m
The figure represents a swimming pool with vertical walls and a plane rectangu→ lar sloping floar PQRS. The water surface ABCD is a rectangle 20m by 12m and the depth is on at one end. and 1im at the other. Calculate
(a) the volume of water in
the po
pool. (b) the angle at which the
floor in inclined to the horizontal.
it is proposed to cover the floor and the four vertical walls, as shown in the figure, with water-proofing material at a cost of 70% per sq.m. Calculate, to the nearest #, the cost of the proposed
·work.
10. A triangle has a perimeter
of 19 cm and its ahortest side in 4 cm, Calculate the lengths of the remaining two sides of this triangle: in each of the following
The triangle is similar to another triangle in which the longest two sides are. 3 and 5 cm. (b) the lengths of the
sides of the triangle are in geometric progression.
Kaleld is represented on
Sa map by the quadrilateral
ABCD in which AB-2.8cm, AC=1.6cm, APK1.35cu,
tvo:
equal circlea
intersect at A and B. The centre 0 of one circle lies on the circumference of the other. The straight line APQ cuts the circle at P and Q. Prove that
ZAQU=+/APB.
PO-PB
if BP is produced to cut the circle with centre 0 at R, then AR// BQ.
14. (a) In a factory, x metal
hooks and (x+4) plastic hooks are produced every minute. Write down expressions for the times, in seconds, to produce one metal hook and one plastic hook respectively. (b) From the result of
if a metal hook takes 14 seconds longer to- produce than a plastto hook, form an equation: in x and solve itu. llence calculate the total number of hooks produced altogether in 8 minutes.
15. In the figure
AUCD 18 # parallelogram. M, N are the mid-pointa of the sides CD and Ch respectively. AMX, ANY, DCY and BCX are straight lines. Prove that...
8
·AADM = AXCM.
BACKD
a
gram
(c) Area of ABCD »
ABYXD.
The normal work in an office was done by A, H, each working 6 days a A did 42% of the work and/ B did 40% of it. In a certain week, the work was suddenly doubled; C did no more than usual, A incres- sed his daily amount of work by 150% for 4 days auth- then foll 111 and could do no more. By how much par cent did ʼn have to increase. his week's work to pet everything done?
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