molecules of ice, water and water vapour have equal intermolecular distances
2
The density P of a spherical ball of diameter d and mass m is given by
คำตอบ
(C)
p = \(\frac{6m}{\pi d^3}\)
3
A metal rod of density 7000 kgm-3 and cross-sectional area of 0.001257m2 has a mass of 1.76kg. Calculate its length.
คำตอบ
(A)
0.20m
4
The pressure in a liquid
คำตอบ
(C)
is the same in all directions at a given point
5
The property of a fluid that is used to determine its suitability as a lubricant is its
คำตอบ
(B)
viscocity
6
The area under a velocity-time graph represents
คำตอบ
(B)
distance covered
7
In the absence of gravitational force, the weight of the body is
คำตอบ
(B)
zero
8
Which of the following propeties is not considered in choosing mercury as a thermomemetric liquid?
คำตอบ
(A)
density
9
A stone of mass 300g is released from rest from the top of a bulding of height 100m. Determine the kinetic energy gained by the stone when it is a quarter way down from the point of release.[g = 10 ms-2]
คำตอบ
(C)
75.0J
10
A body of mass 120g placed at the 10cm mark on a uniform metre rule makes the rule settle horizontally on a fulcrum places at 35cm mark. Calculate the mass of the rule
คำตอบ
(D)
200g
11
Two simple pendulum A and B of equal lengths and of masses 5g and 20g respectively are located in the same environment. The periods TA and TB of their respective oscillations are related by the equations
คำตอบ
(C)
TA = TB
12
An object of mass 5.0 kg moves with a velocity of 10ms-1. Calculate its momentum.
คำตอบ
(A)
50.0 kgms-1
13
A coin is pushed from the edge of a laboratory bench with a horizontal velocity of 15.0 ms-1. If the height of the bench from the floor is 1.5m, calculate the distance from the foot of the bench to the point of impact with the floor [g = 10ms-2]
คำตอบ
(C)
8.22m
14
Which of the following statements correctly defines a simple machine? A device
คำตอบ
(C)
with which work can be done easily
15
The radius of a wheel is 30.0 cm and that of its axle is 6.0cm. Calculate the effort required to lift a load of 120.0N using this machine. Assuming 100% efficiency
คำตอบ
(C)
24.0N
16
A hypsometer is used for determining
คำตอบ
(A)
steam point
17
Which of the following equations shows how how the linear expansivity (\(\alpha\)) and the cubic expansivity (\(\gamma\)) of a material are related?
คำตอบ
(D)
\(\gamma = 3 \alpha\)
18
Which of the following statements about anomalous expansion of water are correct? i. There is contraction between 0oC and 4oC. ii. There is expansion between 0oC and 100oC. iii. The volume is minimum at 4oC. iv. The volume is maximum at 4oC
คำตอบ
(C)
i and iii only
19
Which of the following assumptions is not valid for an ideal gas ?
คำตอบ
(D)
molecules move at constant speed between collisions
20
A body is pulled over a distance of 500m by a force of 20N. If the power developed is o.4 kW, calculate the time interval during which the force is applied
คำตอบ
(C)
25.0s
21
A metal of mass 200g at a temperature of 100oC is placed in 100g of water at 25oC in a container of negligible heat capacity. If the final steady temperature is 30oC, calculate the specific heat capacity of the metal. [specific heat capacity of the water is 4200 Jkg-1 K-1]
คำตอบ
(A)
150 Jkg-1K-1
22
Ether produces a cooling effect when it is poured on the hand because it has
คำตอบ
(C)
high latent heat of vaporization
23
Which of the following statements about the image formed by a plane mirror is not correct?
คำตอบ
(C)
it is formed by actual intersection of rays
24
The image formed by a convex mirror is always
คำตอบ
(D)
virtual, erect and diminshed
25
A ray undergoes a minimum deviation at 40o when it is incident on equilateral triangular glass prism. Calculate the refractive index of the prism
คำตอบ
(C)
1.53
26
Total internal reflection occurs in an optical prism when light rays
คำตอบ
(B)
are incident in the prism at an angle greater than the critical angle
27
The speed of light in a certain medium is V while its speed in a vacuum is C. The absolute refractive index of the medium is
คำตอบ
(B)
\(\frac{C}{V}\)
28
An object is placed 20.0cm in front of a converging lens of focal length 15.0cm. Calculate its image distance
คำตอบ
(D)
60.0cm
29
Presbyopia is a defect of the eye resulting from
คำตอบ
(A)
weak ciliary muscles
30
The focal length of the eye-piece of an astronomical telescope is f1, while the focal length of the object is f2. Fro normal adjustment, the angular magnification is given by
คำตอบ
(A)
\(\frac{f_2}{f_1}\)
31
two sound waves have frequencies of 12Hz and 10Hz. Calculate their beats period
คำตอบ
(A)
0.5s
32
The main difference between echo and reverberation is that
คำตอบ
(B)
the time interval between incident sound and reflecte sound is shorter for reverbration
33
Which of the following statements about the electromagnetic waves is correct?
คำตอบ
(D)
white light occupies a region beyond ultraviolet rays
34
The correct relationship between "G" and "g" in a gravitational field is given by the equation (Where the symbols have their usual meanings)
คำตอบ
(B)
g = \(\frac{GM}{R^2}\)
35
The capacitance of a parallel-plate capacitor
คำตอบ
(D)
is greater with a dielectric between the plates than without a dielectric.
36
When the pointed end of an uncharged optical pin is brought near the cap cf a positively charged electroscope, it is observed that the gold
คำตอบ
(A)
collapse slowly
37
Which of the following substances does not conduct electricity?
คำตอบ
(B)
glass
38
The unit of capacitance is
คำตอบ
(A)
farad
39
An ammeter with a full scale deflection of 10mA has an internal resistance 0.5\(\Omega\). calculate the resistance of the shunt required to adapt it to read up to 3A
คำตอบ
(A)
0.0167\(\Omega\)
40
The resistivity, \(\mathit{P}\), of a material of length l, cross-sectional area A, resistance R, is given by the equation
คำตอบ
(A)
\(\mathit{P} = \frac{RA}{l}\)
41
A wire of length 30cm is moved with a speed of 2ms-1 at right angles to a magnetic field of flux density 0.4T. calculate the emf induced in the wire
คำตอบ
(B)
0.24V
42
Which of the following practices will lead to losses in electrical power transmission?
คำตอบ
(C)
transmitting at relatively low voltage and high current
43
For photoelectric emission, the threshold frequency is the
คำตอบ
(B)
minimum fraquency of incident radiation required to eject elecrons
44
Which of the following properties is not applicable to X-rays? They
คำตอบ
(C)
are deflected by magnetic field
45
Uranium-234 disintegrated to form Thorium-230 by emitting
