The magnitude of the resultant of two mutually perpendicular forces, F1 and F2 is 13N, if the magnitude of F1 is 5N, what is the magnitude of F2?
Trả lời
(C)
12.0N
3
Two points on a velocity time-graph have coordinates (5s, 10ms-1) and (20s, 20ms-1). Calculate the mean acceleration between the two points
Trả lời
(A)
0.67ms-1
4
A thin film of liquid is trapped between two glass plates. The force required to pull the plates apart will increase if the
Trả lời
(C)
area of the liquid surface in contact with the plates is increased
5
A block-and-tackle system is used to lift a load of 20N through a vertical height of 10m. if the efficiency of the system is 40%, how much work is done against friction?
Trả lời
(C)
300J
6
Which of the following devices are used to measure pressure? i. Aneroid barometer. ii. hydrometer. iii. hygrometer. iv. manometer.
Trả lời
(D)
i and iv
7
A piece of wood of mass 40g and uniform cross-sectional area of 2cm2 floats upright in water. The length of the wood immersed is
Trả lời
(C)
20cm
8
The pressure on the gas of constant gas thermometer at the ice point is 325mm of mercury and at the steam point is 875mm of mercury. Find the temperature when the pressure of the gas is 190mm of mercury
Trả lời
(B)
243k
9
A column of air 10.0cm long is trapped in a tube at 27oC. What is the length of the volume at 100oC?
Trả lời
(A)
12.4cm
10
A mass of gas at 7oC and 70cm of mercury has a volume of 1200cm3. Determine its volume at 27oC and pressure of 75cm of mercury.
Trả lời
(A)
1200cm3
11
An electric heater is used to melt a block of ice of mass 1.5kg. If the heater is powered by a 12V battery and a current of 20A flows through the coil, calculate the time taken to melt the block of ice at 0oC. [specific latent heat of fusion of ice = 336 x 103Jkg-1]
Trả lời
(B)
35.0min
12
From the kinetic theory of gases, temperature is a
Trả lời
(D)
physical property and is proportional to the average kinetic energy of the molecules
13
A vibrator of frequency 60Hz is used in generating transverse stationary waves in a long thin wire, If the average distance between successive nodes on the wire is 45cm, find the speed of the transverse waves in the wire.
Trả lời
(B)
54ms-1
14
When the tension in a sonometer wire is doubled, the ratio of the new frequency to the initial frequency is?
Trả lời
(C)
\(\sqrt2\)
15
In a sound wave in air, the adjacent rarefactions and compressions are separated by a distance of 17cm. If the velocity of the sound wave is 340ms-1. Determine the frequency
Trả lời
(C)
1000Hz
16
Light of wavelength 5000 x 10-8cm travels in free space with a velocity of 3 x 108ms-1. What is its wavelength in glass of refractive index 1.5?
Trả lời
(A)
3333 x 10-8cm
17
The magnification of the image of an object placed in front of a convex mirror is \(\frac{1}{3}\). If the radius of curvature of the mirror is 24cm, what is the distance between its object and its image?
Trả lời
(D)
32cm
18
The plane mirrors in a kaleidoscope are usually placed
Trả lời
(A)
at an angle of 60o
19
A far sighted person cannot see objects that are less than 100cm away. If this person wants to read a book at 25cm, what type and focal length of lens does he need?
Trả lời
(C)
convex, 33cm
20
When a yellow card is observed through a blue glass, the card would appear.
Trả lời
(A)
black
21
Dispersion of light by a glass prism is due to the
Trả lời
(B)
different speeds of the various colours in glass
22
Which of the following pairs is NOT part of the electromagnetic spectrum? i. Radio waves. ii. Beta rays. iii. Gamma rays. iv. Alpha rays
Trả lời
(D)
ii and iv
23
Two insulated charged spheres of different sizes and carrying opposite charges are connected together by a metallic conductor. Current will flow from one sphere to the other until both sphere
Trả lời
(B)
are at the same potential
24
When a number of identical small magnets are arranged in a line, the strength of the resultant magnet
Trả lời
(A)
ia largest when they are arranged end to end
25
A bar magnet is most effectively demagnetized by
Trả lời
(D)
heating the magnet
26
The resistance of a 5m uniform wire of cross-sectional area 0.2 x 10-6m2 is 0.425. What is the resistivity of the material of the wire?
Trả lời
(D)
1.70 x 10-8\(\Omega\)m
27
Three resistors, with substances 250\(\Omega\), 500\(\Omega\) and 1k\(\Omega\) are connected in series. A 6V battery is connected to either end of the combination. Calculate the pot3ential difference between the end of the 250\(\Omega\) resistor.
Trả lời
(B)
0.86V
28
A calibrated potentiometer is used to measure the e.m.f. of a cell because the
Trả lời
(C)
potentiometer takes no current from the cell
29
An ammeter of resistance 1.0\(\Omega\) has a full-scale deflection of 50mA. Determine the resultant full-scale deflection of the meter when a shunt of 0.0111\(\Omega\) is connected across its terminals.
Trả lời
(C)
500mA
30
The electrochemical equivalent of silver is 0.0012gC-1. If 36.0g of silver is to be deposited by electrolysis on a surface by passing a steady current for 5.0mins, the current must be
Trả lời
(B)
100A
31
When a radiation strikes a metal surface, electrons may be ejected from the metal. The maximum kinetic energy which may be acquired by an ejected electron depend on the
Trả lời
(C)
wavelength of the radiation
32
Which of the following is TRUE of the particles emitted in radioactive disintegration?
Trả lời
(D)
the beta particle is deflected more than the alpha particle in a magnetic field
33
Eight alpha decays and six beta decays are necessary before an atom of 2 \(^{238}_{92}U\) achieves stability. The final product in the chain has an atomic number of
Trả lời
(C)
82
34
An object is placed at 5.6 x 10-4m in front of a converging lens of focal length 1.0 x 10-nm. The image formed is
Trả lời
(C)
Real, inverted and magnified
35
The function of a 5-A fuse included in a circuit supplying a household refrigerator with power is to keep the
Trả lời
(B)
keep current supplied to the refrigerator below 5A
36
The fig above shows a uniform circular object, center R and diameter PS. A circular section 6 and Diameter PR is cut from it. if PQRS is a straight line, where is center of gravity of the figure
Trả lời
(D)
A point between R and S
37
A simple pendulum of mass m moves along an arc pf a circle radius R in a vertical plane as shown above. What is the work done by gravity in a downward swing through the angle q to 0 degree
Trả lời
(B)
MgR (1- cos θ)
38
A block of mass m is held in equilibrium against a vertical wall by a horizontal force. If the coefficient of friction between the wall and the block is µ, the minimum value of the horizontal force is
Trả lời
(C)
(1+µ)mg
39
In the fig above W\(_1\) = 200g, and W\(_2\) =450g. Calculate the extension of the spring per unit load.
[g = 10ms\(^{-2}\)]
Trả lời
(C)
6.0 x 10 -3mN-1
40
The air column as shown above is set into vibration by the turning fork. In this State of resonance, the waves in the air column will be
