A man standing on a lift that is descending does not feel any weight because
คำตอบ
(C)
the lift's acceleration is same as acceleration due to gravity
2
Two balls X and Y weighing 5 g and 50 kg respectively were thrown up vertically at the same time with a velocity of 100 ms1 .How will their positions be one second later?
คำตอบ
(D)
X and Y both be 500 m from the point of throw
3
If it takes an object 3s to fall freely to the ground from a certain height, what is the distance covered by the object?
คำตอบ
(C)
45 m
4
An object of mass 2 kg moves with a velocity of 10 ms1 round at circle of radius 4 m. Calculate the centripetal force on the object
คำตอบ
(C)
50 N
5
A carpenter on top of a roof of 20.0m high dropped a hammer of mass 1.5 kg and it fell directly to the ground. the kinetic energy of the hammer just before hitting the ground is?
[g = 10 ms-2]
คำตอบ
(C)
300 J
6
If a tube of small radius opened at both ends is placed in a liquid, the liquid will
คำตอบ
(C)
falls below the liquid level if the liquid does not wet the glass
7
An object weighs 22 kg in water and 30kg in air. what is the upthrust exerted by the liquid on the object.
[g = 10 ms2]
คำตอบ
(D)
80 N
8
A metal of volume 40 cm3 is heated from 30 °c to 90 °c, the increase in volume is
คำตอบ
(E)
no correct option
9
A copper wire was subjected to a tensile stress of 7.7 x 10\(^7\). Calculate the strain of the wire.
[Young modules = 1.1 x 10\(^11\) Nm\(^{-2}\)]
คำตอบ
(C)
7.0 x 10-4
10
I. High thermal capacity.
II. High sensitivity.
III.Easy readability.
IV. Accuracy over a wide range of temperature
From the statement above, the qualities of a good thermometer are
คำตอบ
(D)
II, III and IV
11
A machine is used to lift a load of 20 N through a height of 10 m. if the efficiency of the machine is 40%, how much work is done?
คำตอบ
(B)
500 J
12
I. Density of the liquid.
II. Depth below the surface of the liquid.
III. Surface area of the liquid.
In which of the statement above will pressure be dependent?
คำตอบ
(A)
I and II only.
13
Which of the following could be effectively used to reduce friction?
คำตอบ
(B)
grease
14
Which of the following types of waves needs a medium for propagation?
คำตอบ
(A)
sound waves
15
Which of the following electromagnetic waves has the highest frequency?
คำตอบ
(C)
x - rays
16
A perfect emitter or absorber of radiant energy is a
คำตอบ
(B)
black body
17
The ground is always cold at night because the
คำตอบ
(B)
earth radiates heat to the atmosphere at night
18
A cannon is fired from town X,after how long is the sound heard at a town Y 4.95 km away?
[velocity of sound in the air = 330 ms-1]
คำตอบ
(D)
15 s
19
The phenomenon that shows that increase in pressure lowers the melting point can be observed in
คำตอบ
(D)
regelation
20
A block of aluminum is heated electrically by a 30 w heater if the temperature rises by 10°c in 5 minutes, the heat capacity of the aluminum is
คำตอบ
(A)
900 JK-1
21
Steam burn is more severe than that of boiling water because
คำตอบ
(B)
steam possesses greater heat energy per unit mass
22
I. change of state
II. Diffusion
III. Radiation
IV. Osmosis
which of the processes above can be explained using the kinetic theory?
คำตอบ
(D)
I, II and IV
23
Three similar cells each of e.m.f 2 v and internal resistance 2Ω are connected in parallel, the total e.m.f and total internal resistance are respectively
คำตอบ
(B)
2 v, 0.7Ω
24
When the human eye loses its power of accomodation, the defect is known as
คำตอบ
(B)
presbyopia
25
When a red rose flower is observed in blue light, what colour does the observer see?
คำตอบ
(E)
No correct option
26
The capacitance of a parallel plate capacitor is 20 μf in air and 60 μf in the presence of a dielectric. What is the dielectric constant?
คำตอบ
(C)
3.0
27
A certain far - sighted person cannot see object that are closer to the eye than 50 cm clearly. Determine the power of the converging lens which will enable him to see at 25 cm
คำตอบ
(B)
0.02 D
28
The eclipse of the sun occurs when the
คำตอบ
(A)
moon is between the sun and the earth
29
Which of the following is a property of steel?
คำตอบ
(C)
it can be used for making permanent magnets
30
In measuring high frequency a.c, the instrument used is the
คำตอบ
(D)
hot wire ammeter
31
If the charge of electricity is K wh is N4, what is the cost of operating an electrical appliance rated 250 v,2 A for six hours?
คำตอบ
(B)
N12
32
Under which of the following conditions do gases conduct electricity?
คำตอบ
(B)
low pressure and high p.d
33
Two inductors of inductance 4 II and 8 II are arrange in series and a current of 10 A is passed through them. What is the energy stored in them?
คำตอบ
(A)
600 J
34
Which of the following materials has an increase in resistance with temperature?
คำตอบ
(B)
metals
35
The bond between silicon and germanium is
คำตอบ
(A)
covalent
36
A radioactive isotope has a decay constant of 10-5s4. Calculate half life
คำตอบ
(C)
6.93 x104s
37
The electrical properties of germanium can be altered drastically by the addition of impurity. This process is referred to as
คำตอบ
(D)
dopping
38
If the threshold frequency for tungsten is 1.3 x 1015Hz, what is its work function?
[H = 6.6 x 10-34 Js]
คำตอบ
(A)
8.58 x 10-19 J
39
Which of the following will be applied when a metal Y is used to electroplate another metal X in electrolysis?
คำตอบ
(D)
Y is the anode and very high current is used
40
The diagram above shows two vectors at right angles to each other. The value of the resultant vector is
คำตอบ
(B)
10.0 N
41
The diagram above show the positions of a cone. The position which can be described as neutral equilibrium is represented as
คำตอบ
(A)
Z only
42
The correct expression for the potential at a point distance r from a charge q in an electric field is?
คำตอบ
(D)
\(\frac{q}{4πε_or}\)
43
An image in a convex lens is upright and magnified 3 times. If the focal length of the lens is 15 cm, what is the object distance?
คำตอบ
(A)
10 cm
44
A length of wire has a frequency of 225Hz when stretched by a force of 225N. If the force increased to 324N, what is the new frequency of vibration?
คำตอบ
(A)
270 Hz
45
In the circuit above, three resistors, 2Ω, 4Ω and 12Ω are connected in parallel and a 12V battery is connected across the combination. The current flowing through the 12Ω resistors is
