乌二第張七第2
日五十月一十年申戊歷夏
報日僑華 WAH KIU YAT PO
五期
日三月二十年九六九一屡公年七十五國民華中育教僑華
起
做於實際半髅上
些參考碳剂。
故的製程'料 室 必可以发行。
(RB)
糕
三、學生美勳參與政治上和弊....
註 野生一實的治提在灌 所,研發的的的其到秦些游美方出學認有擠目
機醌共次欲動與清榮面独生無關的標 入時會影原聲嗚,密,法況,都設運學學的指興學?
所隱爲,兼岡支生,引有則是到的的運運係政治運使
或海
旺行不的流
延的?中心減用这宙政能行计
及現的的難。
開辦磨
和理接在有穢
以但壓
誰?麵不們的溫
學的
和黨動
受理推
,策力,
夜此興
海邦
餐進智人,同生活全育法
設外分性公麻權力官將席、治較方寓行的速度要不的麻齒齋 彩温現施,及借大個確與的中俄港
能爲者来克服上述的弊
受政谶的
聯合公報全文 第四屆專上學生研討會
,遙成其系的降,則對
,伙他們用無力的 的實質顧已改變,同時 治的目的,則學生運動 和利用,以逹成他們
度效泡是耐補苑行呀及变矮治的绑顴
製造
文中學會考試題預習
物理科
(D)
陸永熾
PHYSICS (9)
15. Solution.
Work
(a) Force Force is something which changes or tends to change the state of rast of a body.
of its uniform motion in a straight line.
- When a force acts on a body with the. point. of application of the force: being. displaced, then work is said to be done. it 13 measured by the product of the applied force. and the displacement of the point of application; Power: - The rate of working is called power. It determines the amount of work done by a man or a machine in a unit time.
pounda lb.
Quantities
Force
dyne
nowton kguwt.
Work
erg
joule m-kg.wt.
ft. -pdi, ft-lb.wt.
Powel
arg/sec
sec.
watt mokg.wt.
M/sab
ft.-pd1/8ec
ft.-lb/sec3
horsepower
he underlinsa unite are gravitational unita rest being absolute unita,
pay.
(1 lb.)(1 ft./sec)
• (16 oz.)(12 in./sec2)
(16 x 28.3 gm. )(12 x 2.54 cm./sec. (16 x 28.3 x 12 x 2.54) dyies
10 x 28.3 x 12 x 2.54
horsepower
32.2 x 12 x 2.54)
550 ft-lb/seu
550 x 32.2 ft-pdl/sec
550 x 32,2 x 12 x 2.54 cm-pdl/see
550 x 32.2 x (12 x 2.54)2 x 16 x 28.30m-ay
550x 32.2 x(12x2.54)f x 16 x 28.3.erg/sec 550 x 32.2 x (12 x 2.54)? x 16 x 28.3
107 1 103/
(11) The power developed at 30 m.p.h. (ex88ft/sec)
1120 x 88 x 88.
32 x 45 x 2 x 550
5.48 h.p
When converting speeds in .p.h. to ft. per sec., it is convenient to remember that 60. m.p.h.88 ft./sec.
so 40.m.pih. = = x88 ft/sec
mh.
x 88 ft./960
By conservation of energy: the kinetic energy possesso. by the bob at its lowest. point B mist equal to it. potential energy at ▲ or with respect to B.
K.E. at B
Where is the mass of bob
velocity of bob at:i heignt of hob raised
BD
BS = 100(1 cos30")=13.4 om.
No2 x 980 x 13:4
162 cm/sec.
Ans The velocity of the pendulum bob at ita
Lowest point is 162-cm/sec.
Mass of bucket, m, 3 lb.1 Forcey causing: motion
( x 32) pal.
Total:mass being accelerated:
(2x3)+
2 x 32
981
163.5 cm/sec
18plate the hanging masa,
the resultant vertical accelerating force is (10g - T) dyne.
(hhere Tis the tension of the cord)
10g - T-10 x 163.5
T 9810-1635
B175 dynes
Check: Isolate the block, the "accel
force is T.
T50 x 163.5.
B175 dynes.
Ans. The acceleration of the sliding block:
is 163.5 cm./sec.?
The tension of the cord, then, is 8175 dynes.
Questions ior this weeke
17. (a) An iren shot of mass 3 kg is dropped from the top of a tower 80m, high, The distance follen
at the end of each second is shown in the table
came (seconds).
Distance (metres) - D
20 45 80
1.Constra
a table of seven columns with vue for each second of time. Put time and distance fallen in the first two columns, and the following quantities in the other columns: (1) the neight above the ground at each tina di) the potential energy of the shot at mach
time
111) the specu ecquared by the falling shot at
each time
(iv) the kinetic energy of the shot at each time.
(v) the total energy of the ahot at each time Ta the energy conserved during: the fall?! An arrangement constructed as shown in figure: The inclination of the slope is 1 in 12; the length of the crank of the windlass, is 1 ft. and the diameter of the axle 13 2 inches and the efficiency of the whole arrangement is 60 per cent. Find the effort required in. raising a load of 150 lb.
jindlass
Initial vel. of the car
After 30 sec. Its vel.
(The acceleration,
x 88
88
ft./980
X:58 ft./500
●qual
The force, F, which produces an
acceleration, a, dn
"129,59, m, 18" given:
88.
1120
pd1
1120 x 88
32. x 45
This force is constant as
acceleration remains constant
Since
Power- rate of working
Long as t the
(1)
Force x velocity.
Therefore, the power developog at 20 m.possi
-1120 x 88 88-
32 x 45
1120 x 88 x 88.
32 x 45 x 3 x 55
3.65. h-p.
ft./sec.
When the buckets are b ft. apart, each bucket has travelled 3 ft. The time required La calculated from the motion equation
have 30 »
49 x 3 16
3.03. sec.
Ans. The time required by the buckets to be
6 ft. apart is 3.03 sec.
(a) The force causing motzon
of the system is the suspending weight 10 go, wt. or 10g dynes. The total mass being.
accelerated...
(50+10)gm,
(509m
(a) what is meant by coefficient of static and
Kinetic friction:
(b) Describe an experiment to determine th
coefficient of atatic friction of a body o plane.
(c) Block A weighs 4 lb and block B weighs 8 Ib..
The coefficient of kinetic friction between axi, surfaces is 0.25. Find the force Pnecessary to "drag block B the left at constant speed.
(1) if A rest on B and moves with it.
(11) I? A is held at rest,
(iii) if A and B are connected by a flexible
cord. passing around a fixed frictionless pulley.
CA
A
B
Therefore, applying the equation
ma
10g
10)a
10g
ingan
A
R