JAMB UTME - Physics - 1987
Vraag 1 Verslag
When a transformer has more secondary windings than primary windings, it
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Vraag 2 Verslag
A constant force of 40N acting on a body initially at rest gives an acceleration of 0.1ms-2 for 4s. Calculate the work done by the force
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X = ut + 12 at2
= (0 x 4) + (12 x 0.1 x 4 x 4)
= 0.8m
workdone = force x distance
= 40 x 0.8
= 32J
Vraag 3 Verslag
he coefficient of static friction between a 40kg crate and concrete surface is 0.25. Find the magnitude of the minimum force needed to keep the crate stationary on the concrete base inclined at 45o to the horizontal. [G = 10ms-1]
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momentum force = R5nθ - μ Rcosθ
Fm = (40 x 10 x sin 45) - (40 x 10 x 0.25 x cos 45)
= 212N
Vraag 4 Verslag
In which of the following are the substance arranged in descending order of their thermal conductivities?
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Vraag 5 Verslag
A 50kg block is dropped from a point 10cm above as shown in the fig above. if the force constant of the spring is 4.0 x 104Nm-1, find the maximum compression of the spring [g = 10ms-2]
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Vraag 6 Verslag
he lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 150Hz?
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In stretched strings the overtones are in odd multiple of Fo.
F1 = 3Fo
= 3 x 40 = 120Hz
F2 = 5Fo
= 5 x 40
= 200Hz
Vraag 7 Verslag
What type of reaction is represented by the following scheme? 21X + 21Y + 32Z + 10n + energy
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Vraag 8 Verslag
Hot water is added to three times its mass of water at 10oC and the resultant temperature is 20oC. What is the initial temperature of the hot water?
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Heat loss = heat gained
mh x ch x θ h = mc x cc x θ c
mh x ch x (θ - 20) = mc x cc x (20 - 10)
ch = cc ; mc = 3mh
therefore, θ = 50oC
Vraag 9 Verslag
In the figure above, M and N are insulated metal spheres in contact. A negatively charged ebonite rod P is I brought near M. When M and N are Separated and the rod is taken away, which of the following statements is correct
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Vraag 11 Verslag
A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is
Vraag 12 Verslag
In the above, a voltage V is applied across the terminals P and Q. The voltage across the 1 ohm resistor is
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Vraag 13 Verslag
A galvanometer of resistance 20Ω
is to be provided with a shunt that 110
of the whole current in a circuit passes through the galvanometer. The resistance of the shunt is
Vraag 14 Verslag
A man walks 8km north and then 5km in a direction 60o east of north. Find the distance from his starting point
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R = √52+82−2×5×8×cos120o
R = √129
= 11.36km
Vraag 15 Verslag
A wave has a frequency of 2Hz and a wavelength of 30cm. The velocity of the wave is
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V = Fλ
= 2 x 0.3
= 0.6ms-1
Vraag 16 Verslag
A jet engine develops a thrust of 270Ns when the velocity of the exhaust gases relative to the engine is 300ms-1. What is the mass of the material ejected per second?
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Thrust = force x time
thrust = m(v−u)t x t1
270 = m(300 - 0)
m = 0.90kg
Vraag 19 Verslag
Which of the following phenomena explains the fact that a house whose roof is coated with white paint will be cooler in the hot season than one coated with black paint ?
Vraag 20 Verslag
The fig above represents the main sequence of energy conversion at Kainji dam. What is the efficiency of the system?
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Vraag 22 Verslag
Two capacitance of 6μ F and 8μ F are connected in series. What additional capacitance must be connected in series with this combination to give a total of 3μ F
Vraag 23 Verslag
The fig above shows two connected bodies of masses M1 and M2 in equilibrium under gravity. The tension in the upper string is
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Vraag 24 Verslag
A cube of side 10cm and mass 0.5kg floats in a liquid with only 15 of its height above the liquid surface. What is the relative density of the liquid?
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Height below liquid = 1 - 15 = 45
volume of cube = 103cm3
volume of liquid displaced = 45 x 1000
= 800cm3
density of liquid displaced;
= 500800
= 0.625cm-1
Vraag 25 Verslag
A ray of light is incident at an angle of 30o on one top surface of a parallel-sided glass block of refractive index 1.5. The ray finally emerges from the lower surface. What is the angular deviation of the emergent ray?
Vraag 26 Verslag
When the length I of a piece of wire under constant tension is varied, the relationship of the frequency of the vibration fα / is
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F = 12L√Tm
Vraag 27 Verslag
22,000J of heat is required to raise the temperature of 1.5kg of paraffin from 20oC to 30oC. Calculate the specific heat capacity of paraffin.
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22,000 = 1.5 x c x (30 - 20)
c = 1466Jkg-1oC-1
Vraag 28 Verslag
The distance between the fixed points of a centigrade thermometer is 20cm. What is the temperature when the mercury level is 4.5cm above the lower mark?
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20cm .... 100oC
4.5cm .... θ
0cm ....0oC
4.5−020−0 = 0−0100−0
θ = 22.5oC
Vraag 29 Verslag
Which of the following statements supports the assumption that light travels in straight lines?
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Vraag 30 Verslag
A current of 0.5A flows through a resistor when connected to a 40-V battery. How much energy is dissipated in 2 minutes?
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Electrical energy = IVT
= 0.5 x 40 x 2 x 60
= 2400J
Vraag 31 Verslag
An elevator of mass 4800kg is supported by a cable which can safely withstand a maximum tension of 60 000N. The maximum upward acceleration the elevator can have is
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a = Fm
= 60000−(4800×10)4800
= 2.5ms-2
Vraag 32 Verslag
If an object is placed in front of two mirrors inclined at 90o, how many images will be formed?
Vraag 33 Verslag
The direction of the magnetic field at a point in the vicinity of a bar magnet is
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Vraag 34 Verslag
The velocity time graph above describes the motion of a particle between two points P and Q. What is the distance between P and Q?
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Vraag 36 Verslag
Calculate the amount of heat required to convert 2kg of ice at 2oC to water at 0oC. [specific heat capacity of ice = 2090Jkg-1oC-1, specific latent heat of fusion of ice = 333kJkg-1]
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Q = mL + mcθ
= (2 x 333000) + (2 x 2090 x 2)
= 674 360J
Vraag 37 Verslag
A pool of water appears to be 1.0m deep when viewed vertically from above. If the refractive index of water is 1.33, what is the actual depth of the pool?
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n = real depthapparent depth
1.33 = real depth1
real depth = 1.33cm
Vraag 38 Verslag
A body rolls down a slope from a height of 100m. its velocity at the foot of the slope is 20ms-1. What percentage of its initial potential energy is converted into kinetic energy? [g = 10ms-1]
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P.E = mgh = 1000m joules
K.E = 12 mv2 = 200m joules
%converted = 200m1000m x 100
= 20%
Vraag 39 Verslag
Four lenses are being considered for use as a microscope objective. Which of the following focal lengths is most suitable?
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Vraag 40 Verslag
When two parallel wires carry currents in opposite directions, the force on either wire is
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Vraag 41 Verslag
If a beaker is filled with water it is observed that the surface of the water is not horizontal at the glass-water interface. This behavior is due to
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Vraag 42 Verslag
A load of 5N gives an extension of 0.56cm in a wire which obeys Hooke's law. What is the extension caused by a load of 20N?
Vraag 43 Verslag
A boat at anchor is rocked by waves whose crest are 100m apart and whose velocity is 25ms-1. At what interval does the wave crest reach the boat?
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Distance between the boat and crest = 100m
time = 10025
= 4sec
Vraag 44 Verslag
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Vraag 45 Verslag
An object 3.0cm high is placed 60.0cm from a converging lens whose focal length is 20.0cm. Calculate the size of the image formed
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F = UVU+V
20 = 60×V60+V
V = 30cm
similarly, UV = height of objectheight of image
6030 = 3h
h = 1.5cm
Vraag 46 Verslag
As a result of air at the top of a barometer, the height of the mercury column is 73.5cm when it should be 75.0cm; the volume of the space above the mercury is 8.0cm3. Calculate the correct barometer height when the barometer reads 74.0cm and the volume of the space above the mercury is 6.0cm3.
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Using, P1P1 = P2P2
(75 - 73.5) x 8 = (X - 74) x 6
X = 76cm
Vraag 47 Verslag
The length of a side of a metallic cube at 20oC is 5.0cm. Given that the linear expansivity of the metal is 4.0 x 10-5k-1, find the volume of the cube at 120oC .
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Y = V2−V1V1×θ
3 x 4 x 10-5 = V2−125125×(120−20)
V2 = 126.50cm3
Vraag 48 Verslag
Which of the following units is equivalent to kgms-1?
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kgms-1 = massdistance
since, F = ma = kgms-1 = N
kgms-1 = Ns
