其二第張六第 日十月九年未己腦裏
1980
中學會考試題預習專欄
物理
(四)
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Physics (4)
Anever to Exercise 2
1(a)
A
WAH KIU YAT PO
報日僑華
二期星
日十三月十年九七九一縻公年八十六國民中青教儒鞌
2
Load
2gh
1.6
In the figure, AC -
AB - HD
(u) LAQB
E
123
hoad
=
240
50g
500N
and (BAD = 4/BAC. Find the values of x and y.
(b) PO = P8,
-1
-
i
500 E
1.6
(c) If BP
LAPR.
is produced to cut the circle with centre (at 1, then i AR // BO
2(10)(12)
15.492ms1, Ans.
(b) Let the common ve
velocity
required be v ma
·
Initial momentum of the system
- (10)(~;) kgmu ̄1.
Fian momentum of the system
(10412)v kgme
-1
By conservation of
linear momentum,
10v i
(10+12)v
E' = 312,5N. Ans.
(d) Let the tension in the
string connected to the 50kg-block be T newtons
T
1.6 effort When effort = 600N
B
T
600
=.1.6
* 960 N
Hence, the net force
3. A manufacturer's catalogued
prices are 25% above cust,
but buyers are allowed a discount. of 8% off these
"What is the
prices.
manufacturer's nét gaine per cent?
4. Divide a load of 120kg
between A, B, C so that
A bas half as much again as B, and B has twice as much as C?
R
B
14.
115 kg
a mg
10 kg
As shown in the figure above, let T. tension in the
string,
acceleration of the system.
Apply Newton's 2nd law to
the blocks seperately,
15(10)-T - 15a
T-10(10) 108
(1)+(2):
-
50 - 25a
-2
a
2 ms
+
Ans
(b) Substitute a - 2 into (2)
T-10(10)
10(2)
Tx 120N. ADS
(c) Apply the formula
2
Let Vi
2
* + 2as
be the velocity of
the 15kg-block when it
strikes the floor. The initial velocity is Oms-1
•
V
M
10 22i
10
•
(15.492)
- 7.042 ms-1.
5.
acting on the 50kg-block
- 960-50g
- 960-500
= 460N
ABB.
Apply Newton's 2nd law,
460 =
50(a)
#
- 9.2 me-2.
Ans,
(c) Let the average retarding
force exerted by the ground on the pile be
F newtons, Hence,
work done against F
- loss in kinetic energy
+ loss in potential
energy
Work done against P
·F(0.5)
=
+
Loss in kinetic energy
19
(10+12)v
$(22)(7.042)2
- 545.5J/
Loss in potential energy
(10.12)(10)(0,5)
110J
.*. P(0.5) (545.5+110)
F1311 N. Ans.
3(a)(i)
a ms2
Ans: The block will move
upwards with accelera- tion 9.2 ms-2.
5(a)(i) Upthrust of water.
on the cube
- weight of the cube
900(0.1)3g 900(0.1)3(10) -
- 9N
Ans.
(ii) Let the volume of the
cube immerged in water
be Vi
が、
Upthrust on the cube
(1000)(g)(V1)
1000(10) 9"
y = 9x10-4
Since the volume of
the cube
(0.1)3
*
6.
In the figure. The circle RPQ touches BC at P. AB produced at R and AC
produced at 0. If [ARC = 70° and B&C
50°.
Calculate
BRP and PRQ. (Geometry theorem need not be quoted when used.)
B
In the figure, XY// BC, BC-8 cm, XY5cm; the lines RC, XY are 2cm apart. Find the ares of AAXY.
(Geometry theorem need not be quoted when used.)
7. In AABC, if a:bre - k:5:6,
find cosa.
8. If A+B+C = 180°,
14. In the figure, AD is a
tangent to the circle ABC and AC is, tangent to the. circle AHD. Prove that (a) AANC and ADBA are
sigilar,
(b) AB = BC BD,
(c) If the tangent at C
and Ŋ meet at T and
[CTD = 120°, calculate ZCAD.
15. Find, in c.e. the volume of
a closed cylindrical tube, internal diameter 2mm, internal length 35cm (take X-2). is filled with
which weighs 13.6 g
mercury
per c.c., find the weight of the mercury, correct to
10 KD.
16. A's income is 60% of B's
income and A's expenditure is 70% of R's expenditure. If A's income in 75% of
B's expenditure, find the rate of A's,eaving to B's saving.
1980
中學會考試題預習專欄
simplify
2
K
-
2(a)(2) 2(2)(2)
- 8
= 2.8284 ms
Ans.
(d) Let the time required for
the 15kg-block to reach the floor be t (seconds). Apply the formula
(e)
2
+ jat2
initial velocity
*4at2
Substitute & 2
2.
t-
+(2)+2 √
- 1.4142.
T
130kg +2014+104600N
smooth horizontal plane
As shown in the figure above, let the tensions in the strings be T. and T. the acceleration of the system be a,
(1)+(2)+(3):
I
(10+20+30) a
a = 10 ms «*.*
(ii) Substitute a 10 into (1) and (2), we have
T1
==
T
2
(b)(i)
a ms2
600-10(10) 500N.
30(10)
300N.
Ans
Ans
1 x 10-3
CosAsinC – sin(A+B)cos(B+C) COSĄCONC2 + Cos(A+B)cos(B+C}
Section B
fraction of the cube intersed
9.
2008
9 x 10
Д
1 x 10TM
4cm
Sin
數字推理 (+)
9 10
600-T1 T1-2
Apply Newton's 2nd law to the blocks seperately,
- 10a
D
5cm
(b) As shown in the figure
below
(1)`
*
208
(2).
=
T2 300
(3)
600 -
-2
(7:20 kgm2>
10.
P
Water
(1000 m2)
A U
B
-
C
R
S
In the figure, AB // DC,
AB =2cm, BC • Gem, NC = 5cm,
AD 4cm, find
(a)
{8} ZADC of ABCD.
數字推理練習七
***B*****
選出下列有關的正確答案,並在它的下面畫
15kg
115 kg 10 kg
As shown in the figure above let the velocity of the 10kg-block be v2 when it reaches the level at A.
hence,
2 2
2(a)(2) 2(2)(2)
8
the string slackens, sume the block moves à meters farther before drops
down, 2
2
2(g)(h)
2
་
8
30kg 120kg 10 ke
- 6:00 N
fi
As shown in the figure above, f,, f, and f, are the frictional forces of the 10kg, 20kg and 30kg-blocks respectively.
13
-0.2(10)(10) - 20N
0.2(20)(10)
0.2(30)(10)
40N
*
GUN
Let the acceleration of the system be a', the' tensions in the strings be T' and
'2
1
Apply Newton's 2nd. law to the blocks seperately,
600-T*,-20 =.10a '
1
ནཱ་དྡྷ – ཡ''ཊྛམནཾ༦ * 20'
Let his depth of oil
A cross-sectional
area of the cube (= 0.01 sq.m.) Upthrust due to oil on the cube
"(720)(g) (ha)
72001A
Upthrust due to water on the cube
1000(g)(0.1–h)À
- 10,000(0,1-4)A
Total upthrust exerted ou the cube
-
7200A+10,000(0.1-h)A 1000A-2800h A (1000-2800k) A Weight of the cube 900(0.1)(A)(g)
900A
Total upthrust
weight of the cube (1000-2800h) A - 900 A
h = 0.0357m
the cube rises,
0:0357m ». 1cm
≈ 0.0357m-0.01m
-0.0257m
In the figure, ABCDEF in a regular hexagon of side 7 cm and the triangles are all isosceles, each having its equal sides 8cm long. It is then folded along the edges of the hexagon to form a right pyramid with ABCDEF as base and. with the six points P, Q, R, S, T, U coming together at the vertex, say V, calculate
(a) height of the pyramid, (b) volume of the pyramid,. (c) angle between the face
VBC, and the base ARCDEF.
11. A particle P starts from
a point 0. and moves along a straight line so that its velocity, v m/s, after time t sec in given by
v 30 6t5. Calculate (a) tlle velocity with which
-the particle leave the
point 0),
(b) the time taked for the vulicity of P to reach 50 /
(c) the minimum velocity
of Pa
1.下列五姐線段中,那一組的線段互相垂直?
A
B
C
D
E
X X 11 = xx
2.下列五怨線段中,那一組的線段互相平行?
A
E
B
X
D
3.下列五個圖形中,那一個與其他四個不相同?
A
B
E
B
4.下列五個圖形中,那一個的周界最短?
A
-C
E
D.
MOUWB
5.下列五個圈形中,那一個的有斜蝶部份佔全
A
?
C
6.下列五個子
P
個真其他四個不相网?
S
T
Өшефа
7. 在下圖中,那一線段與AB平行?
PAC
An:
(1)
1980
(2)
T-60 - 30a1
.(3)
中學會考試題預習專欄
(1)+(2)+(3):
600-120 6Qa'
數學心
** If (x+y)∞ (*~y), show that
1(10)
= 0.4m
Ann: The maximum height
reached by the
10kg-block is
0.4+2 2.4m above the floor.
2(a) Let the velocity of the
pile driver as it strikes the pile be v, IE
F
V
2
By conservation of energy
mgh
where m
"mags of the pile-driver
- 10kg
and h-height fallen
- 12
4(a) V.R. ** 4.
.*. M.A. (c) Let the minimum effort
required be E
a' - 8 ms2.
-2
Ans.
(ii) Substitute a'
into (1),
500N.
Substitute a' into (3),
明德出版社交長连接 Mathematios 4
hence deduce that
(x2+xy+y2) ac (x2-xy+y2).
Exercise 2
13.
ANE
8
Anaver ALL questions in Section A and any Six
questions in Section B
T
- 300N.
2
Section A
1. If x
y
(b)
H.A.
· x 100% V.R.
MAL 100%
40%
40
22
2
3/2 .. 2/3 and 3/2+2/3, simplify
In the figure, two unequal circles intersect at A and
ху
·
Ans..
B. The centre 0 of une cirole Jies on the circumference of the other. The straight line APQ outa the circle at P and Q.
* OC OD
ZA OE OB
OP
Prove that
QCD
RDE
SFG
TEF
B.在下面中,那一線侵觀日日亙相叠道?
PBC
QCF
RAH
SAB
TFE