JAMB UTME - Physics - 1987
Ajụjụ 2 Ripọtì
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
Akọwa Nkọwa
F = UVU+V
20 = 60×V60+V
V = 30cm
similarly, UV = height of objectheight of image
6030 = 3h
h = 1.5cm
Ajụjụ 3 Ripọtì
When two parallel wires carry currents in opposite directions, the force on either wire is
Akọwa Nkọwa
Ajụjụ 4 Ripọtì
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]
Akọwa Nkọwa
momentum force = R5nθ - μ Rcosθ
Fm = (40 x 10 x sin 45) - (40 x 10 x 0.25 x cos 45)
= 212N
Ajụjụ 5 Ripọtì
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]
Ajụjụ 8 Ripọtì
A wave has a frequency of 2Hz and a wavelength of 30cm. The velocity of the wave is
Akọwa Nkọwa
V = Fλ
= 2 x 0.3
= 0.6ms-1
Ajụjụ 9 Ripọtì
Which of the following units is equivalent to kgms-1?
Akọwa Nkọwa
kgms-1 = massdistance
since, F = ma = kgms-1 = N
kgms-1 = Ns
Ajụjụ 10 Ripọtì
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.
Ajụjụ 11 Ripọtì
A cube of side 10cm and mass 0.5kg floats in a liquid with only \( \frac{1}{5} \) of its height above the liquid surface. What is the relative density of the liquid?
Akọwa Nkọwa
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
Ajụjụ 12 Ripọtì
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?
Akọwa Nkọwa
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
Ajụjụ 13 Ripọtì
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 ?
Ajụjụ 14 Ripọtì
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?
Ajụjụ 15 Ripọtì
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.
Akọwa Nkọwa
Using, P1P1 = P2P2
(75 - 73.5) x 8 = (X - 74) x 6
X = 76cm
Ajụjụ 16 Ripọtì
When the length I of a piece of wire under constant tension is varied, the relationship of the frequency of the vibration \( \alpha \)/ is
Akọwa Nkọwa
F = 12L√Tm
Ajụjụ 17 Ripọtì
The direction of the magnetic field at a point in the vicinity of a bar magnet is
Akọwa Nkọwa
Ajụjụ 18 Ripọtì
The fig above represents the main sequence of energy conversion at Kainji dam. What is the efficiency of the system?
Akọwa Nkọwa
Ajụjụ 19 Ripọtì
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
Akọwa Nkọwa
a = Fm
= 60000−(4800×10)4800
= 2.5ms-2
Ajụjụ 20 Ripọtì
Akọwa Nkọwa
Ajụjụ 21 Ripọtì
he lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 150Hz?
Akọwa Nkọwa
In stretched strings the overtones are in odd multiple of Fo.
F1 = 3Fo
= 3 x 40 = 120Hz
F2 = 5Fo
= 5 x 40
= 200Hz
Ajụjụ 22 Ripọtì
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?
Akọwa Nkọwa
n = real depthapparent depth
1.33 = real depth1
real depth = 1.33cm
Ajụjụ 23 Ripọtì
What type of reaction is represented by the following scheme?
\[ {}^{2}_{1}X + {}^{2}_{1}Y + {}^{3}_{2}Z + {}^{1}_{0}n + \text{energy} \]Ajụjụ 24 Ripọtì
Two capacitance of \(6\,\mu\text{F}\) and \(8\,\mu\text{F}\) are connected in series. What additional capacitance must be connected in series with this combination to give a total of \(3\,\mu\text{F}\)
Ajụjụ 25 Ripọtì
Isotopes are nuclei which have
Ajụjụ 26 Ripọtì
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?
Akọwa Nkọwa
Thrust = force x time
thrust = m(v−u)t x t1
270 = m(300 - 0)
m = 0.90kg
Ajụjụ 27 Ripọtì
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]
Akọwa Nkọwa
P.E = mgh = 1000m joules
K.E = 12 mv2 = 200m joules
%converted = 200m1000m x 100
= 20%
Ajụjụ 28 Ripọtì
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]
Akọwa Nkọwa
Q = mL + mcθ
= (2 x 333000) + (2 x 2090 x 2)
= 674 360J
Ajụjụ 29 Ripọtì
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?
Ajụjụ 31 Ripọtì
A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is
Ajụjụ 32 Ripọtì
A current of 0.5A flows through a resistor when connected to a 40-V battery. How much energy is dissipated in 2 minutes?
Akọwa Nkọwa
Electrical energy = IVT
= 0.5 x 40 x 2 x 60
= 2400J
Ajụjụ 33 Ripọtì
Which of the following statements is TRUE of photoelectric effect?
Ajụjụ 34 Ripọtì
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
Akọwa Nkọwa
Ajụjụ 35 Ripọtì
If an object is placed in front of two mirrors inclined at 90o, how many images will be formed?
Ajụjụ 36 Ripọtì
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 .
Akọwa Nkọwa
Y = V2−V1V1×θ
3 x 4 x 10-5 = V2−125125×(120−20)
V2 = 126.50cm3
Ajụjụ 37 Ripọtì
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?
Akọwa Nkọwa
Ajụjụ 38 Ripọtì
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
Akọwa Nkọwa
Ajụjụ 39 Ripọtì
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?
Akọwa Nkọwa
20cm .... 100oC
4.5cm .... θ
0cm ....0oC
4.5−020−0 = 0−0100−0
θ = 22.5oC
Ajụjụ 40 Ripọtì
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
Akọwa Nkọwa
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
Ajụjụ 42 Ripọtì
Which of the following statements supports the assumption that light travels in straight lines?
Akọwa Nkọwa
Ajụjụ 43 Ripọtì
A man walks 8km north and then 5km in a direction 60o east of north. Find the distance from his starting point
Akọwa Nkọwa
R = √52+82−2×5×8×cos120o
R = √129
= 11.36km
Ajụjụ 44 Ripọtì
Four lenses are being considered for use as a microscope objective. Which of the following focal lengths is most suitable?
Akọwa Nkọwa
Ajụjụ 45 Ripọtì
The fig above shows two connected bodies of masses M1 and M2 in equilibrium under gravity. The tension in the upper string is
Ajụjụ 46 Ripọtì
A galvanometer of resistance \(20\,\Omega\) is to be provided with a shunt that \(\frac{1}{10}\) of the whole current in a circuit passes through the galvanometer. The resistance of the shunt is
Ajụjụ 48 Ripọtì
In which of the following are the substance arranged in descending order of their thermal conductivities?
Akọwa Nkọwa
