JAMB UTME - Physics - 2019
Ibeere 1 Ìròyìn
The momentum of a car moving at a constant speed in a circular track
Awọn alaye Idahun
Movement of an object in a circle with an acceleration towards its center is provided by change in velocity and centripetal force a α V α Fc
Ibeere 2 Ìròyìn
The lead-acid accumulator consists of
Awọn alaye Idahun
- the positive pole is lead peroxide (PbO2
)
- the negative pole is head
- the electrolyte is H2
SO4
Ibeere 3 Ìròyìn
Calculate the velocity ratio of a screw jack of pitch 0.2cm if the length of the tommy bar is 23cm
Awọn alaye Idahun
P = 0.2cm, L = r = 23cm
| VR | = | 2?rP | = | 2?LP | = | 2?×230.2 | = | 230? |
Ibeere 4 Ìròyìn
Electrons were discovered by
Awọn alaye Idahun
Electrons were discovered by J.J. Thompson. In the late 19th century, he performed a series of experiments using cathode ray tubes, which are glass tubes containing low-pressure gas and electrodes. By applying high voltage, he observed a beam of negatively charged particles traveling from the negative electrode to the positive electrode. He concluded that these particles, which he called "corpuscles," were fundamental units of negative charge and later were renamed electrons. This discovery led to the development of the modern understanding of atomic structure and the electron's role in it.
Ibeere 5 Ìròyìn
When the temperature of a liquid is increased, its surface tension
Awọn alaye Idahun
Surface tension or elasticity of a fluid decreases with increased in temperature
Ibeere 6 Ìròyìn
A cone is in unstable equilibrium has its potential energy
Awọn alaye Idahun
In unstable equilibrium, potential energy decreases as the height decreases.
Ibeere 7 Ìròyìn
Which of the following characteristics of a wave is used in the measurement of the depth of the Sea?
Awọn alaye Idahun
Depth of sea can be measured by echo, a reflected sound waves.
Ibeere 8 Ìròyìn
Which of the following readings cannot be determined with a meter rule?
Awọn alaye Idahun
Meter rule has a reading accuracy of 0.5mm or 0.05cm, thus measurement is M ± 0.05cm i.e 2.00, 2.05, 2.50, 2.55 etc.
The reading that cannot be read is 2.56cm.
Ibeere 9 Ìròyìn
A body was slightly displaced from its equilibrium position. Which one of the following is a condition for its stable equilibrium
Awọn alaye Idahun
The condition for stable equilibrium of a body that has been slightly displaced from its equilibrium position is "an increase in the potential energy of the body." When an object is at its equilibrium position, it has a minimum potential energy. When the object is displaced from its equilibrium position, it has a higher potential energy. For the object to be in stable equilibrium, it must be able to return to its equilibrium position after it has been displaced. If the potential energy of the object increases as it is displaced, it means that the equilibrium position is a point of stable equilibrium. This is because the object will experience a restoring force that will push it back towards its equilibrium position, as the potential energy decreases. Therefore, an increase in potential energy is a condition for a body to be in stable equilibrium after it has been slightly displaced from its equilibrium position. An increase in kinetic energy or height does not necessarily indicate stability, as it depends on the specific situation and other factors at play.
Ibeere 10 Ìròyìn
When water is boiling, it
Awọn alaye Idahun
When water is boiling, it changes from a liquid state to a gaseous state called steam. This happens when the water is heated to its boiling point, which is when it reaches a temperature of 100 degrees Celsius (212 degrees Fahrenheit) at sea level. As the water is heated, it absorbs energy and the molecules start to move faster and faster, eventually reaching a point where they escape into the air as steam. The temperature of the water during boiling does not change, as all the energy is being used to break the bonds between the water molecules rather than increasing the temperature. Therefore, the options "gets hotter," "increase in mass," and "decreases in mass" are not correct when describing what happens when water is boiling.
Ibeere 11 Ìròyìn
Which of the following media allow the transmission of sound waves through them?
I. air
II. liquid
III. solids
Awọn alaye Idahun
Sound waves are disturbances in a medium that propagate through the medium and transfer energy from one point to another. The transmission of sound waves depends on the physical properties of the medium, including its elasticity and density. Air (Option I) is a gas that is compressible and has a relatively low density, which makes it an excellent medium for transmitting sound waves. Liquids (Option II) are also able to transmit sound waves, although the speed of sound in liquids is slower than in gases because liquids are more dense and less compressible. Solids (Option III) are able to transmit sound waves as well, but their density and elasticity make them more rigid, which means that sound waves in solids tend to be transmitted as elastic waves or mechanical waves, rather than as acoustic waves. Therefore, the correct answer is "I, II, and III".
Ibeere 12 Ìròyìn
Gases conduct electricity under
Awọn alaye Idahun
Gases conduct electricity under low pressure and high voltage
Ibeere 13 Ìròyìn
The value of T in the figure above is
Awọn alaye Idahun
Tsin30 + Tsin30 =40
2Tsin30 = 40
Tsin30 = 40/2 = 20
T(12 ) = 20
T = 20 x 2 = 40N
Ibeere 14 Ìròyìn
The equilibrium position of objects in any field corresponds to situation of
Awọn alaye Idahun
The equilibrium position of an object in any field corresponds to the situation of minimum potential energy. This means that at the equilibrium position, the object has the lowest possible potential energy within the field. In other words, the forces acting on the object are balanced, and the object is not being pushed or pulled in any direction. Therefore, the object will remain at rest at the equilibrium position unless it is acted upon by an external force. Of the options given, the correct answer is "minimum potential energy".
Ibeere 15 Ìròyìn
The volume of 0.354g of helium at 273°C and 114cm of mercury pressure is 2667cm\(^{3}\). Calculate the volume
Awọn alaye Idahun
m = 0.354g, T1
= 273°C = 273 + 273 = 576K
P1
= 114cmHg, V1
= 2667cm3
at STP
T2
= 273K, P2
= 76cmHg, V2
= ?
| P1 V1 T1 | = | P2 V2 T1 |
| V2 | = | 114 × 2667 × 27376 × 576 | = | 2000.25cm3 |
Ibeere 16 Ìròyìn
In Sunlight, a blue flower looks blue because we see the flower by the light it
Awọn alaye Idahun
In sunlight, a blue flower looks blue because it reflects blue light. When sunlight falls on an object, the object can either absorb, transmit, or reflect the light. The color of an object that we see is determined by the light that is reflected by that object. For example, if an object appears blue, it is because it reflects blue light and absorbs other colors. In the case of a blue flower in sunlight, the petals of the flower reflect blue light and absorb other colors. This reflected blue light enters our eyes, and our brain interprets it as the color blue. Therefore, we see the blue flower as blue because it reflects blue light, and that is the color that enters our eyes. In summary, the reason why a blue flower looks blue in sunlight is that it reflects blue light and absorbs other colors.
Ibeere 17 Ìròyìn
A train has an initial velocity of 44m/s and an acceleration of -4m/s\(^{2}\). Calculate its velocity after 10 seconds
Awọn alaye Idahun
The velocity of the train after 10 seconds can be calculated using the formula: v = u + at where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Substituting the given values, we get: v = 44 m/s + (-4 m/s^2) x 10 s v = 44 m/s - 40 m/s v = 4 m/s Therefore, the velocity of the train after 10 seconds is 4m/s. Answer option D is correct. Explanation: The train has an initial velocity of 44 m/s and an acceleration of -4 m/s^2. The negative sign indicates that the acceleration is in the opposite direction to the initial velocity, which means that the train is slowing down. After 10 seconds, the train's velocity decreases by 40 m/s (4 m/s^2 x 10 s) to reach a final velocity of 4 m/s.
Ibeere 18 Ìròyìn
The pitch of a screw jack is 0.45cm and the arm is 60cm long. If the efficiency of the Jack is 75/π %, calculate the mechanical advantage.
Awọn alaye Idahun
P = 0.45cm, L = 60cm, Eff = 75/π%
| VR | (Screw | system) | = | 2πrP | = | 2πLP |
| M.A | = | Eff% × VR100 | = | 75π | × | 1100 | × | 2π × 600.45 | = | 75 × 800300 | = | 200 |
Ibeere 21 Ìròyìn
An object is acted upon by a system of parallel three causing the object to be in state equilibrium. Which of the following statement is not correct
Awọn alaye Idahun
all the parallel forces must be equal in magnitude and direction
Ibeere 22 Ìròyìn
During the transformation of matter from the solid to the liquid state, the heat supplied does not produce temperature increase because
Awọn alaye Idahun
When a solid is heated to its melting point, the heat supplied is used to overcome the intermolecular forces holding the molecules in a fixed position, resulting in the breaking of these bonds. As a result, the solid transforms into a liquid without any change in temperature. This is because the heat energy supplied is used in breaking the bonds between molecules rather than increasing the kinetic energy of the molecules, which is what causes an increase in temperature. Therefore, the correct option is: "all the heat is used to break the bonds holding the molecules of the solid together."
Ibeere 23 Ìròyìn
The conductivity of gases at low pressure can be termed as
I. hot cathode emission
II. thermo ionic emission
III. cold cathode emission
IV. Field emission
Awọn alaye Idahun
As conduction of gases is at low pressure and high voltage, called field or cold cathode emission.
Ibeere 24 Ìròyìn
A vibrator causes water ripples to travel across the surface of a tank. The wave travels 50cm in 2s and the distance between successive crests is 5cm. Calculate the frequency of the vibrator
Awọn alaye Idahun
The frequency of the vibrator can be calculated using the formula: frequency = speed / wavelength where speed is the speed of the wave, and wavelength is the distance between successive crests. In this case, we are given that the wave travels 50cm in 2s, which means the speed of the wave is: speed = distance / time = 50cm / 2s = 25cm/s We are also given that the distance between successive crests is 5cm, which is the wavelength. Therefore, the frequency of the vibrator is: frequency = speed / wavelength = 25cm/s / 5cm = 5Hz So the correct answer is 5Hz.
Ibeere 25 Ìròyìn
According to kinetic molecular model, in gases
Awọn alaye Idahun
According to the kinetic molecular model, in gases, the molecules are very fast apart and occupy all the space made available. This means that gas molecules are in constant random motion and they move freely in all directions without any regular arrangement. They collide with each other and with the walls of the container, exerting pressure. The temperature of the gas is related to the average kinetic energy of the gas molecules. The higher the temperature, the faster the gas molecules move, and the higher the kinetic energy.
Ibeere 26 Ìròyìn
Which of the following statements is/are correct for a freely falling body?
I. the total is entirely kinetic
II. the ratio of potential energy to kinetic energy is constant
III. the sum of potential and kinetic energy is constant
Awọn alaye Idahun
The correct answer is "III only". A freely falling body is one that is falling under the influence of gravity and experiences no other force or constraint. In this situation, the total energy of the body is conserved, meaning that the sum of its potential and kinetic energy remains constant. The potential energy of a body is directly proportional to its height above the ground, and its kinetic energy is directly proportional to its velocity. As the body falls, its potential energy decreases and its kinetic energy increases, but the total energy remains constant. Statement III is correct because the sum of potential and kinetic energy is indeed constant for a freely falling body. Statement I is incorrect because the body has both potential and kinetic energy, so the total energy is not entirely kinetic. Statement II is incorrect because the ratio of potential energy to kinetic energy is not constant for a freely falling body, as both are changing as the body falls.
Ibeere 27 Ìròyìn
In semi-conductor, the carriers of current at room temperature are
Awọn alaye Idahun
In a semiconductor, the carriers of current at room temperature are both electrons and holes. Semiconductors are materials with properties that are in between those of conductors (e.g. metals) and insulators (e.g. rubber). At room temperature, a semiconductor crystal contains both free electrons and positively charged vacancies called holes. When a voltage is applied across the semiconductor, the electrons move towards the positive end of the circuit and the holes move towards the negative end. This movement of charge carriers constitutes an electric current. In summary, both electrons and holes can carry current in a semiconductor at room temperature, making the correct answer.
Ibeere 28 Ìròyìn
When a girl moves towards a plane mirror at a speed of 4.0m/s, the distance between the girl and her image reduces a speed of
Awọn alaye Idahun
| v | = | dt | or | v | α | d |
d = x, v = 4m/s
d = 2x, v = ? (girl and image)
| v | = | 2 × 4x | = | 8 | ms |
Ibeere 29 Ìròyìn
- angle of dip is zero at the magnetic equator
- angle of variation is the same as angle of declination.
Awọn alaye Idahun
- angle of dip is zero at the magnetic equator
- angle of variation is the same as angle of declination.
Ibeere 30 Ìròyìn
A well 1km deep is filled with a liquid of density \(950\text{kg/m}^3\) and \(g = 10\text{m/s}^2\), the pressure at the bottom of the well is
Awọn alaye Idahun
P = Pa + ρgh = (1.00 × 105
) + (950 × 10 × 1000)
P = 105
+ (95 × 105
) = 105
(1 + 95) = 96 × 105
P = 9.6 × 106
N/m2
Ibeere 31 Ìròyìn
The mass of a nucleus is the
Awọn alaye Idahun
The mass of a nucleus is the total number of its protons and neutrons. The protons and neutrons are the subatomic particles that make up the nucleus of an atom. The mass of an atom is mostly concentrated in its nucleus, and the electrons orbiting the nucleus have a much smaller mass. Therefore, the mass of an atom is mostly determined by the number of protons and neutrons in its nucleus. The number of protons determines the element, and the number of neutrons can vary, resulting in isotopes of that element.
Ibeere 32 Ìròyìn
The following are some units
I. Ns
II. Non
III. \( \mathrm{Nm}^{-2} \)
IV. \( \mathrm{J^\circ K}^{-1} \)
V. \( \mathrm{JKj}^{-1} \)
What are the units of latent heat?
Awọn alaye Idahun
Latent heat or specific latent heat = L
| Heat | energy | = | mL | or | L | = | Hm | = | energymass |
Ibeere 33 Ìròyìn
A metal rod has a length of 100cm at \(200^\circ C\). At what temperature will its length be 99.4cm. If the linear expansivity of the material of the rod is \(2 \times 10^{-5}C^{-1}\)
Awọn alaye Idahun
The linear expansivity of a material describes how its length changes with temperature. If the linear expansivity is given as 2 × 10^-5/°C, this means that for every 1°C change in temperature, the length of the material will change by 2 × 10^-5 times its original length. Given that the rod has a length of 100 cm at 200°C, we can use this information to find its length at a different temperature. If we let L be the length of the rod at temperature T, we can write the relationship as follows: L = 100 cm * (1 + 2 × 10^-5 * (T - 200°C)) To find the temperature at which the rod will have a length of 99.4 cm, we can set L equal to 99.4 cm and solve for T: 99.4 cm = 100 cm * (1 + 2 × 10^-5 * (T - 200°C)) 99.4 cm / 100 cm = 1 + 2 × 10^-5 * (T - 200°C) 0.994 = 1 + 2 × 10^-5 * (T - 200°C) -0.006 = 2 × 10^-5 * (T - 200°C) -0.006 / 2 × 10^-5 = T - 200°C -0.006 / (2 × 10^-5) = T - 200°C -0.006 / (2 × 10^-5) + 200°C = T So the temperature at which the rod will have a length of 99.4 cm is approximately equal to -0.006 / (2 × 10^-5) + 200°C, or -100°C. Therefore, the answer is -100°C.
Ibeere 34 Ìròyìn
Which of the following is/are the limitations to the Rutherford's atomic models?
I. It is applicable when energy is radiated as electrons are revolving
II. It is applicable when energy is radiated in a continuous mode
III. It is applicable to an atom with only one electron in the other shell
Awọn alaye Idahun
Rutherford assumed that (I) energy is radiated when electrons are revolving (II) energy is radiated in a continuous mode. These are limitations of Rutherford's model
Ibeere 35 Ìròyìn
The part of the human eye that does similar work as the diaphragm of a camera lens is the
Awọn alaye Idahun
The part of the human eye that does similar work as the diaphragm of a camera lens is the iris. The iris is the colored part of the eye and is responsible for controlling the amount of light that enters the eye. Just like the diaphragm in a camera lens, the iris can adjust its size to allow more or less light into the eye. This helps to regulate the amount of light reaching the retina, which is responsible for sensing light and transmitting the image to the brain.
Ibeere 36 Ìròyìn
The limiting frictional force between two surfaces depends on
I. the normal reaction between the surfaces
II. the area of surface in contact
III. the relative velocity between the surfaces
IV. the nature of the surfaces
Awọn alaye Idahun
- Friction depends on the nature of the surfaces in contact
- Solid friction is independent of the area of the surfaces in contact and the relative velocity between the surfaces.
Ibeere 37 Ìròyìn
If the time of flight is 96seconds, calculate the horizontal range through the point of projection.
Awọn alaye Idahun
Time of flight, T = 96s
R = (Ucosθ) *time* T = 640 × 96 = 61,440m
Ibeere 38 Ìròyìn
Which of the following bodies, each with centre of gravity G, lying on a horizontal table, is/are in unstable equilibrium?
Awọn alaye Idahun
- I and II are in neutral equilibrium. They will roll continuously on the table
- III is a body with high centre of gravity (unstable)
- IV is a body with high centre of gravity (stable)
Ibeere 39 Ìròyìn
The diagram shows four positions of the bob of a simple pendulum. At which of these positions does the bob have maximum kinetic energy and minimum potential energy
Awọn alaye Idahun
At position 1, the bob of the simple pendulum has the maximum potential energy and zero kinetic energy. At position 4, the bob has the maximum kinetic energy and minimum potential energy. To understand this, we need to know that the energy of a simple pendulum is converted back and forth between kinetic energy and potential energy as it swings back and forth. When the bob is at its highest point (position 1), it has the maximum potential energy because it is farthest from the ground and has the most potential to move downward. At this point, the bob has zero kinetic energy because it is momentarily at rest. As the bob swings downward towards the equilibrium point, it gains speed and its potential energy is converted to kinetic energy. At the equilibrium point (position 2), the bob has equal amounts of kinetic and potential energy. As the bob continues to move downward, its potential energy decreases and its kinetic energy increases. At position 3, the bob has minimum potential energy and some amount of kinetic energy. At the lowest point of its swing (position 4), the bob has maximum kinetic energy because it is moving at its fastest speed. At this point, the bob has minimum potential energy because it is closest to the ground and has the least amount of potential to move downward. So, to summarize, the bob has maximum potential energy at position 1, equal amounts of kinetic and potential energy at position 2, minimum potential energy at position 3, and maximum kinetic energy at position 4.
Ibeere 40 Ìròyìn
The volume of a stone having an irregular shape can be determined using?
Awọn alaye Idahun
The volume of a stone with an irregular shape can be determined using a measuring cylinder. A measuring cylinder is a glass or plastic container with a narrow cylindrical shape and markings on the side to indicate the volume it contains. To determine the volume of an irregularly shaped stone, you would fill the measuring cylinder with water, carefully lower the stone into the water, and note the increase in the volume of the water. The difference in the volume of the water before and after the stone was added is equal to the volume of the stone. The meter rule, vernier calliper, and micrometer screw gauge are all measuring instruments, but they are not designed to measure the volume of irregularly shaped objects. The meter rule is a measuring tool used for measuring length. The vernier calliper is used for measuring the diameter of objects, and the micrometer screw gauge is used for precise measurements of small distances.
