WAEC SSCE - Physics - 2015 (Objective)
Pregunta 1 Informe
An object floats in a fluid when it displaces it's
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An object floats in a fluid when it displaces its weight of the fluid in which it floats. This is known as Archimedes' principle. The principle states that any object, wholly or partially immersed in a fluid, experiences an upward buoyant force equal in magnitude to the weight of the fluid displaced by the object. If the buoyant force is greater than or equal to the weight of the object, the object will float in the fluid.
Pregunta 2 Informe
The diagram given illustrates two charged particles W and X. The charges on W and x are respectively
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Pregunta 3 Informe
Two angles of a pentagon are in the ratio 2:3. The others are 60o each. Calculate the smaller of the two angles
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Pregunta 4 Informe
A battery of emf 24V is connected to three resistor P, Q and R as illustrated in the diagram. Determine the voltage across the resistor Q
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Pregunta 5 Informe
The resultant force in a couple is
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In a couple, two equal and opposite forces act on a body, but they are not in the same line. The resultant force of a couple is defined as the algebraic sum of the forces, which is zero because the forces are equal in magnitude and opposite in direction. However, the couple produces a turning effect or torque on the body, which is not zero, and depends on the magnitude of the forces and the distance between them. So the answer is (a) zero.
Pregunta 6 Informe
The diagram above illustrates a block ans tackle pulley system in which an effort E supports a load of 100.0N. If the efficiency of the machine is 75%, calculate the value of E
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Pregunta 7 Informe
The pressure applied to an enclosed fluid to one end id transmitted equally throughout the fluid and to the container walls. This statement is
Detalles de la respuesta
The statement mentioned in the question is related to Pascal's principle. Pascal's principle states that the pressure applied to an enclosed fluid in a container is transmitted equally throughout the fluid and to the container walls. This principle is based on the fact that fluids are incompressible, which means that they cannot be compressed or squeezed into a smaller volume. Therefore, any pressure applied to one end of the fluid is transmitted equally to all parts of the fluid and to the walls of the container. This principle is used in many applications, including hydraulic systems, where a small force applied to one end of a piston is transmitted to a larger force at the other end, allowing heavy loads to be lifted with ease.
Pregunta 8 Informe
An object is placed 20cm from a concave mirror of focal length 15cm. Calculate the linear magnification of the image formed
Detalles de la respuesta
The linear magnification of an image formed by a spherical mirror is given by the formula: magnification = height of image / height of object = -v/u where u is the object distance, v is the image distance and the negative sign indicates that the image is inverted. Given that the object is placed 20cm from a concave mirror of focal length 15cm, we can use the mirror formula: 1/f = 1/u + 1/v Rearranging this formula, we get: 1/v = 1/f - 1/u Substituting the given values, we get: 1/v = 1/15 - 1/20 1/v = (4 - 3)/60 1/v = 1/60 v = 60 cm Now, the magnification can be calculated as: magnification = -v/u = -60/20 = -3 Therefore, the linear magnification of the image formed is 3. Since the image is inverted, the sign of the magnification is negative. So, the correct answer is (d) 3.0.
Pregunta 9 Informe
The mass of the earth is 6.0 x 1024kg and that of the moon is 7.0 x 1022kg. If the distance between them is 4.0 x 108m, calculate the force of attraction between them. [G = 6.7 x 10-11Nm2kg-2]
Detalles de la respuesta
The force of attraction between two masses is given by the formula: F = G(m1m2)/d^2 where: F = force of attraction G = gravitational constant (6.7 x 10^-11 Nm^2/kg^2) m1 = mass of the first object (in kg) m2 = mass of the second object (in kg) d = distance between the centers of the two objects (in meters) Given: Mass of the earth (m1) = 6.0 x 10^24 kg Mass of the moon (m2) = 7.0 x 10^22 kg Distance between them (d) = 4.0 x 10^8 m Gravitational constant (G) = 6.7 x 10^-11 Nm^2/kg^2 Substituting the values into the formula: F = G(m1m2)/d^2 F = 6.7 x 10^-11 x (6.0 x 10^24) x (7.0 x 10^22) / (4.0 x 10^8)^2 F = 1.8 x 10^20 N Therefore, the force of attraction between the earth and the moon is 1.8 x 10^20 N. Answer option (D) is correct.
Pregunta 10 Informe
Which of the following statements about diode is correct?
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Pregunta 11 Informe
The angle which the direction of the earth magnetic field makes with the horizontal at a palace is know as.
Detalles de la respuesta
The angle which the direction of the earth magnetic field makes with the horizontal at a place is known as the "angle of dip". This angle represents the inclination of the Earth's magnetic field lines with respect to the horizontal plane at a particular location. It is also known as the magnetic inclination or magnetic dip angle. The angle of dip varies at different locations on the Earth's surface, and it can be used to determine the position of the magnetic poles.
Pregunta 12 Informe
What type of wave is emitted by a loud speaker?
Detalles de la respuesta
A loudspeaker emits a longitudinal wave. Sound waves are mechanical waves that travel through a medium by compressing and rarefying the particles of the medium. In a longitudinal wave, the displacement of the particles is parallel to the direction of wave propagation. When an electric current is applied to the speaker, it causes the speaker cone to vibrate back and forth, creating areas of compression and rarefaction in the surrounding air. These pressure waves then travel through the air to reach our ears, where they are detected as sound. Therefore, sound waves are examples of longitudinal waves.
Pregunta 13 Informe
A body of mass 1000kg is released from a height of 10m above the ground. Determine its kinetic energy just before it strikes the ground .[g = 10ms-2]
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Pregunta 14 Informe
Which of the following units is the S.I. unit of heat capacity?
Detalles de la respuesta
The S.I. unit of heat capacity is the amount of heat energy required to raise the temperature of a substance by 1 degree Celsius. Heat capacity is measured in Joules per Kelvin (J/K) or Joules per degree Celsius (J/°C). Therefore, the correct option is JK-1, which stands for Joules per Kelvin.
Pregunta 15 Informe
Which of the following statements is correct? When capacitors of different values are connected in series
Detalles de la respuesta
When capacitors of different values are connected in series, the same charge flows through them. This is because the capacitors are connected in a series, so the same current flows through all of them. Since capacitors store charge, the same amount of charge must flow through each capacitor to maintain the same current. However, the voltage across each capacitor will be different, since the voltage drop across each capacitor will be proportional to its capacitance value. So, option A is correct.
Pregunta 16 Informe
What must be connected between the points P and Q to establish a steady current through the incomplete circuit diagram given?
Detalles de la respuesta
To establish a steady current through the incomplete circuit diagram, a cell (battery) must be connected between the points P and Q. A cell provides the potential difference (voltage) required for the current to flow in the circuit. Without a cell, the circuit is incomplete, and no current will flow. Therefore, the correct answer is option C, cell.
Pregunta 17 Informe
An electric generator rated 12 kW, 2 kV distribute power through a cable of resistance 20\(\Omega\). Calculate the power loss in the cable.
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Pregunta 18 Informe
Which of the following concepts is a method of heat transfer that does not require a material medium?
Detalles de la respuesta
The correct answer is radiation. Radiation is a method of heat transfer that does not require a material medium. It involves the transfer of heat through electromagnetic waves, such as infrared radiation. Radiation can occur through a vacuum, which means that it can take place even in the absence of a medium or matter. Examples of radiation include the warmth you feel from the sun, the heat emitted by a fire, and the energy released by a light bulb.
Pregunta 19 Informe
A bullet fired vertically upwards reaches a height of 500m. Neglecting air resistance, calculate the magnitude of the initial velocity of the bullet. [g = 10ms-2]
Detalles de la respuesta
When a bullet is fired vertically upwards, it will continue to move upward until the force of gravity acting downwards slows it down to a stop and then pulls it back down towards the ground. The maximum height the bullet reaches before it falls back down is called the maximum height or the vertex. At the maximum height, the final velocity of the bullet is zero, and the initial velocity is what we are required to find. We can use the equation of motion that relates the initial velocity, final velocity, acceleration and displacement to solve for the initial velocity. This equation is: vf2 = vi2 + 2as where vf is the final velocity (zero), vi is the initial velocity (what we want to find), a is the acceleration due to gravity (-10ms-2 since it is acting in the opposite direction to the motion of the bullet), and s is the displacement (500m). Substituting the known values into the equation, we get: 0 = vi2 + 2(-10ms-2)(500m) Simplifying, we get: vi2 = 10000 Taking the square root of both sides, we get: vi = 100ms-1 Therefore, the magnitude of the initial velocity of the bullet is 100.0ms-1.
Pregunta 20 Informe
\(^{226}_{88}Ra\) emits two alpha particles to produce polonium(po) nuclide. The correct formula for the nuclide?
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Pregunta 21 Informe
The diagram given illustrates a wave form. Determine the speed of the wave
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Pregunta 22 Informe
Water is unsuitable for use as a thermometric liquid because it
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Pregunta 23 Informe
A swimming pool is 2.1m deep. If it contains water of refractive index 1.3, calculate the apparent depth of pool
Detalles de la respuesta
When light enters from one medium to another, its speed changes and it bends. This is called refraction. The refractive index (n) of a medium is the ratio of the speed of light in vacuum to the speed of light in the medium.
The formula for calculating the apparent depth (d') of an object in a medium is given as:
d' = d/n
where d is the actual depth of the object and n is the refractive index of the medium.
In this case, the actual depth of the pool is given as 2.1m and the refractive index of water is 1.3.
Therefore, the apparent depth of the pool can be calculated as follows:
d' = 2.1m / 1.3 = 1.6m
Thus, the apparent depth of the pool is 1.6m. Therefore, the correct option is C.
Pregunta 24 Informe
Which of the following statements describes a body in a stable equilibrium correctly?
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Pregunta 25 Informe
When an air column is set into vibrations, the distance between two consecutive nodes of the resultant wave is
Detalles de la respuesta
When an air column is set into vibrations, it produces sound waves which propagate through the air. In a stationary wave, nodes are the points that appear to be standing still and do not undergo any vibration. They are formed due to the interference between the incident wave and the reflected wave. The distance between two consecutive nodes of a stationary wave is half of the wavelength. This is because a node is formed at the point where the incident wave and reflected wave interfere destructively, resulting in a minimum amplitude or zero displacement. Thus, the distance between two consecutive nodes is equal to half the distance between a node and an antinode (the points of maximum amplitude or displacement), which is half of the wavelength. Therefore, the correct answer is "half of the wavelength".
Pregunta 26 Informe
The barometric reading at a place is 73.5m Hg. Calculate the pressure at a point 30m below the surface of water contained in a reservoir at the place. [g = ms-2, density = 1.2 x 104kg m-3, density of water = 1.0 x 103m-3]
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Pregunta 27 Informe
A girl standing some distance from the cliff claps her hands and hears the echo 0.8s later. calculate her distance from the cliff. [speed of sound in air = 320 ms-1]
Detalles de la respuesta
When sound waves travel, they can bounce off surfaces and return to the listener's ear, creating an echo. The distance between the listener and the reflecting surface can be calculated from the time taken for the sound to travel to the surface and back, and the speed of sound. In this problem, the time taken for the sound to travel to the cliff and back (i.e., the time for the echo to be heard) is given as 0.8s. The speed of sound in air is given as 320 ms-1. Let's call the distance between the girl and the cliff "d". When she claps her hands, a sound wave travels the distance "d" to the cliff and then back again to her ear, covering a total distance of 2d. The time taken for this round trip is equal to the time for the echo to be heard, which is 0.8s. So, we can use the formula: distance = speed x time to calculate the distance "d" between the girl and the cliff. Rearranging the formula, we get: distance = (speed x time) / 2 Substituting the values given in the problem, we get: distance = (320 ms-1 x 0.8s) / 2 distance = 128m Therefore, the girl is 128 meters away from the cliff. So, the correct option is (b) 128m.
Pregunta 28 Informe
A battery of emf 24V is connected to three resistor P, Q and R as illustrated in the given diagram. Determine the voltage across the resistor Q.
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Pregunta 29 Informe
Which of the following statements about a three-pin plug is/are correct. i. The brown wire is the live wire. ii. The fuse is connected to the live wire. iii. The earth wire is coloured blue
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Pregunta 30 Informe
A body is projected with an initial velocity U at an angle O to the horizontal. The time taken by it to reach its maximum height is given by the expression
Detalles de la respuesta
When a projectile is projected with an initial velocity U at an angle O to the horizontal, it follows a parabolic path. The projectile reaches the maximum height at a certain point, then falls back to the ground. At the highest point, the vertical component of the velocity becomes zero. Let's assume that the time taken by the body to reach the maximum height is t. At the maximum height, the vertical component of the velocity becomes zero. Therefore, using the first equation of motion: v = u + gt where v = 0 and u = Usinθ 0 = Usinθ - gt gt = Usinθ t = Usinθ/g Therefore, the time taken by the body to reach its maximum height is given by the expression: t = Usinθ/g Thus, the correct option is: \(\frac{u \text{sin}\theta}{g}\)
Pregunta 31 Informe
An object is placed 15cm from a diverging lens of focal length 12cm. The image of the object formed by the lens in
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Pregunta 32 Informe
A wire of cross-sectional area 0.60mm2 has a restivity of 7.2 x 10-7 \(\Omega\). Calculate the length of wire that will have a resistance of 3\(\Omega\).
Detalles de la respuesta
The formula for calculating resistance is R = ρ(L/A), where R is the resistance of the wire, ρ is the resistivity of the wire material, L is the length of the wire, and A is the cross-sectional area of the wire. We are given the cross-sectional area and resistivity of the wire, as well as the desired resistance. We can rearrange the formula above to solve for L as follows: L = (RA)/ρ Substituting the given values, we get: L = (3 x 0.60 x 10^-6) / (7.2 x 10^-7) = 2.5 meters Therefore, the length of wire that will have a resistance of 3Ω is 2.5m. The correct option is (b) 2.50m.
Pregunta 33 Informe
In an experiment in which a molten substance is allowed to cool, the cooling curve above was obtained. The temperature 60oC is known as the
Detalles de la respuesta
The cooling curve shows how the temperature of a substance changes over time as it cools down. The temperature at which a substance changes from a liquid to a solid is known as its melting point. In the given cooling curve, the temperature at which the slope of the curve changes is known as the melting point. Therefore, the correct answer is the melting point. So, the temperature 60oC is the melting point of the substance.
Pregunta 34 Informe
The crackling noise produced by aluminum roofing sheets on a house during a hot sunny day is a result of
Detalles de la respuesta
The crackling noise produced by aluminum roofing sheets on a house during a hot sunny day is a result of the expansion of the sheets. The heat from the sun causes the metal to expand, and as a result, the sheets push against each other, making the crackling noise. This is because metal expands when heated and contracts when cooled. So during a hot day, the metal expands, and as it cools down in the evening, it contracts, which may also produce a similar noise.
Pregunta 35 Informe
An alternating current supply is connected to an electric lamp which lights with the same brightness as it does with direct current source emf 6v. The peak potential difference of the a.c supply is
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Pregunta 36 Informe
Red light travels faster than blue light when both of them pass through a glass prism because the
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Pregunta 37 Informe
In an experiment in which a molten substance is allowed to cool, the cooling curve above was obtained. The temperature 60oC is known as the
Detalles de la respuesta
The cooling curve shows the temperature changes of a molten substance as it cools. As the molten substance cools, its temperature gradually decreases until it solidifies. The temperature at which the substance changes from liquid to solid state is known as its melting point. In the given cooling curve, the temperature at which the curve plateaus and changes direction from a downward slope to a horizontal line is around 60°C. Therefore, 60°C is the melting point of the substance being tested. Therefore, the correct answer is "melting point".
Pregunta 38 Informe
In a school compound a girl walks 40km due east from the laboratory to the staff room to submit her report. Then she returns and walks 30m due north to her classroom. Determine the magnitude of her displacement from the10m laboratory
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Pregunta 39 Informe
The slope of a straight-line velocity-time graph represents
Detalles de la respuesta
The slope of a straight-line velocity-time graph represents the uniform acceleration. In other words, if the graph is a straight line, the slope of the line represents the rate at which the velocity is changing, which is the acceleration. The steeper the slope, the greater the acceleration, while a zero slope represents zero acceleration, which means the velocity is constant. Therefore, is the correct answer: uniform acceleration.
Pregunta 40 Informe
in a nuclear fission process, the mass defect was 1.2 x 10-5kg. Calculate the energy released. [speed of the light in vacuum = c = 3.0 x 108ms-1]
Detalles de la respuesta
The energy released in a nuclear fission process can be calculated using Einstein's famous equation E = mc^2, where E is the energy released, m is the mass defect, and c is the speed of light. Substituting the given values, we have: E = (1.2 x 10^-5 kg) x (3.0 x 10^8 m/s)^2 E = (1.2 x 10^-5 kg) x (9.0 x 10^16 m^2/s^2) E = 1.08 x 10^12 J Therefore, the energy released in the nuclear fission process is 1.08 x 10^12 J. So the answer is (c) 1.08 x 10^12 J.
Pregunta 41 Informe
All electromagnetic waves in a vacuum have the same
Detalles de la respuesta
All electromagnetic waves in a vacuum have the same speed. This is known as the speed of light, which is approximately 3.0 x 108 meters per second. Regardless of their frequency or wavelength, all electromagnetic waves travel at this same speed in a vacuum, such as in outer space. This is a fundamental property of electromagnetic waves and is a cornerstone of modern physics.
Pregunta 42 Informe
Which of the following radiations constitutes a stream of electrons?
Detalles de la respuesta
Cathode rays constitute a stream of electrons. Cathode rays are a stream of negatively charged particles (electrons) emitted from the negative electrode or cathode in a vacuum tube, also called a cathode ray tube. The electrons are accelerated by an electric field and focused into a beam that can be used for various applications such as in televisions and computer monitors. Therefore, is the correct answer.
Pregunta 43 Informe
A uniform bar AB is balanced on a knife-edge which is 60cm from B by a mass of 22g which hangs at C 10cm from A. Calculate the mass of the bar.
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Pregunta 44 Informe
Which of the following statements about mass and weight are correct? i. Weight is the force of gravity on a body. ii. The mass of a body is the quantity of matter in the body. iii. The weight of a body is greatest at the equator. iv. The mass of a body is greatest at the poles
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Pregunta 45 Informe
When current flows through a moving-coil galvanometer, the force exerted on the pointer depends on the: i. strength of the current. ii. magnetic field strength. iii. length of the coil. Which of the statement(s) above is/are correct?
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Pregunta 47 Informe
Materials that can be stretched and still return to their original forms when the stresses are removed are said be
Detalles de la respuesta
Materials that can be stretched and still return to their original forms when the stresses are removed are said to be elastic. When a force is applied to an elastic material, it deforms in response to the force, but once the force is removed, the material returns to its original shape. This is due to the elastic material's ability to store the energy of deformation and then release it when the force is removed. Examples of elastic materials include rubber bands, springs, and certain types of metals.
Pregunta 48 Informe
Two strings each inclined at an angle 30o to the horizontal are used to hold a bucket of water weighing 20N. Calculate the tension i n each string.
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Pregunta 49 Informe
A quantity of hot water at 100oC is added to 400g of water at 10oC until the temperature of the mixture is 60oC.
Calculate the mass of the hot water added. [Specific heat capacity of water =4200JKg-1 K-1]
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Pregunta 50 Informe
Which of the following units is derived?
Detalles de la respuesta
The derived units are those that can be obtained from the combination of two or more base units. Among the options given, N (Newton) is a derived unit because it is obtained from the combination of kg (kilogram), m (meter), and s (second) through the formula F=ma, where F is the force in N, m is the mass in kg, and a is the acceleration in m/s^2. On the other hand, kg (kilogram), m (meter), and K (Kelvin) are base units because they are independent and cannot be derived from any other unit.
