WAEC - Physics (2002)

1
The force between the molecules of a liquid in contact with that of a solid is
답변
(A)
adhesive
2
A reservoir is filled with a liquid of density 2000kgm^-3. Calculate the depth at which the pressure in the liquid will equal to 9100Nm^-2 [g = 10ms^-2]
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(B)
0.455m
3
A solid weight 45N and 15N respectively in air and water. Determine the relative density of the solid
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(C)
1.50
4
One common characteristics of solids, liquids and gasses is that?
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(C)
their molecules are always in motion
5
A boy travels 8 km eastward to a point B and then 6km northward to another point C. Determine the difference between the magnitude of displacement of the boy and distance travelled by him
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(B)
4.0km
6
The magnitude of the force required to make an object of mass, m move with speed, v in a circular of radius r is given by the expression
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(C)
\(\frac{mv^2}{r}\)
7
A man was moving round a circular path continuously for 4 minutes and covered the following distances in the times stated :
Distance (in metres) 200, 400, 600, 300
Time(in minutes) : 1, 2, 3, 4 respectively. Which of the following statements is correct about the motion of the man?
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(C)
the velocity was uniform
8
A car takes off from rest and covers a distance of 80m on a straight road in 10s. Calculate the magnitude of its acceleration
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(B)
1.60ms^-2
9
An object is released from rest at a height of 25m. Calculate the time it takes to fall to the ground. [g = 10ms^-2]
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(D)
2.24s
10
An object is acted upon by a system of parallel forces causing the object to be in static equilibrium. Which of the following statements is not correct?
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(C)
all the parallel forces must be equal in magnitude and in direction
11
An object A is held in equilibrium as illustrated in the diagram above. Using the data on the diagram determine the magnitude, W of the weight of
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(B)
17N
12
A spiral spring of natural length 30.0cm and force constant of 20Nm^-1 is compressed to 20.0cm. Calculate the energy stored in the spring
답변
(A)
0.1J
13
In the diagram above, AB represents a uniform rod of length 1.50m which is in equilibrium on a pivot at P, If AP = 40cm, calculate the mass of the rod. [g = 10ms^-2]
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(D)
0.800kg
14
Which of the following statements correctly defines quantitatively the work done by a force? the product of the force and the distance moved
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(A)
parallel to the line of action of the force from a reference point
15
a load of mass120kg is raised vertically through a height of 2m in 30s by a machine whose efficiency is 100%. Calculate the power generated by the machine. [g = 10ms^-2]
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(B)
80W
16
A block and tackle system has 6 pulleys. If the efficiency of the machine is 60%, determine its mechanical advantages
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(C)
3.6
17
Which of the following actions will improve the efficiency of the pulley system?
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(A)
reducing the mass of the pulley
18
The ice and steam points of a certain thermometer are -20° and 100° respectively. Calculate the Celsius temperature corresponding to 70° on the thermometer
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(B)
75.0^o
19
The silver coating on the inside of a vacuum flask reduces heat loss by
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(B)
radiation
20
Water of mass 120g at 50oC is added to 200g of water at 10oC and the mixture is well stirred. Calculate the temperature of the mixture. [Neglect heat losses to the surrounding]
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(C)
25^oC
21
Calculate the energy required to vapourise 50g of water initially at 80oC.[specific heat capacity of water = 4.2Jg-1K-1][specific latent heat of vaporisation of water = 2260Jg-1]
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(B)
117,200J
22
What type of motion does the skin of a 'talking' drum perform when it is struck with a drum stick?
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(D)
vibratory
23
A slinky spring fixed at one end is placed horizontally on a table. The free end is displaced parallel to the table and then released. The resultimg wavelength is
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(B)
longitudinal
24
A radio wave has a wavelength of 150m. If the velocity of radio waves is free spaces is 3 x 10\(^8\) ms\(^{-1}\), calculate the frequency of the radio wave
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(D)
2.0 x 10⁶Hz
25
In the wave equation y = E_o, sin(299t - \(\pi\)), E_o represents the
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(A)
amplitude
26
The size of the hole of a pin hole camera is increased. The resultant image formed becomes
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(D)
blurred
27
The refractive index of a medium relative to air is 1.8. Calculate to the nearest degree, the critical angle for the medium
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(C)
34^o
28
A converging lens of focal length 15cm forms a virtual image at a point 10cm from the lens. Calculate the distance of the object from the lens
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(B)
6.00cm
29
In a compound microscope, the image formed by the objective lens is at a distance of 3.0cm from the eye lens. If the final image is at 25.0cm from the eye lens, calculate the focal length of the eye lens
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(B)
2.7cm
30
A pulse of a sound is transmitted from a ship and the reflection from the sea bed is recorded after 0.2s. Calculate the depth of the sea. [Take speed of sound in sea water = 1560ms^-1]
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(B)
156.0m
31
When two notes of nearly equal frequencies are sounded together, a periodic rise and fall in sound intensity can be heard. This phenomenon can be called
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(A)
beats
32
Which of the following instruments is not a wind instrument?
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(D)
xylophone
33
Which of the following actions will not cause an increase in the frequency of a vibrating string?
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(D)
increasing the cross sectional area of the string
34
Which of the following items can be used to compare the relative magnitudes of electric charges on two bodies?
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(B)
gold leaf electroscope
35
Three capacitors each of capacitance 18\(\mu F\) are connected in series. Calculate the effective capacitance of the capacitors
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(C)
6.00\(\mu F\)
36
Two spheres of masses 100kg and 90kg respectively have their centres separated by a distance of 1.0m. Calculate the magnitude of the force of attraction between them. [G = 6.70 x 10^-11Nm^-2kg^-2]
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(D)
6.03 x 10^-7N
37
The magnitude of the gravitational attraction between the earth and a particle is 40N. If the mass of the particle is 4kg. Calculate the magnitude of the gravitational field intensity of the earth on the particle
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(A)
10.0N kg^-1
38
Local actions is normally prevented in a simple electric cell by
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(C)
amalgamating the surface of the zinc plate
39
The lead-acid accumulator consists of a
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(D)
tetraoxosulphate(VI) acid as the electrolyte
40
Which of the following actions will not lead to an increase in the induced e.m.f. in a coil of wire rotating between the poles of a magnet? Increasing the
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(D)
gap between the poles of the magnet
41
A transformer has 400 turns and 200 turns in the primary and secondary windings respectively. If the current in the primary and secondary windings are 3A and 5A respectively. calculate the efficiency of the transformer?
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(B)
83.3%
42
A freely-suspended magnet swinging in a horizontal plane comes to rest with its axis pointing approximately
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(A)
north-south
43

Calculate the inductance L, of the coil in the circuit diagram shown above
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(B)
0.6H
44
In a model of the hydrogen atom, the energy levels Wn are given by the formula Wn = -\(\frac{R}{n^2}\), where n is an integer and R is a constant. Determine the energy released in the transition from n = 3 to n = 2.
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(C)
\(\frac{5R}{36}\)
45
If a radioactive atom emits a beta particle, Its mass number
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(B)
remains the same