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Grade 12 Physics national exam, 2012 E.C. (2020 G.C.)
40 questions · 120 minutes. The first 5 answers are shown with explanations; sit the whole paper timed in the app to get your score and the textbook page behind every question.
- 1.Equilibrium is the state of an object when
- A. The net force and net torque are both zero.
- B. The object has constant angular acceleration.
- C. The net forceZ acting on it is constant.
- D. The object has constant linear acceleration.
Answer: A. An object is in equilibrium when it has no net linear force and no net turning effect, called torque. Thus both the net force and net torque must be zero, as in A. B describes constant angular acceleration; C allows a net force; D describes constant linear acceleration. Textbook: Grade 10, unit 3 · section 3.5.2. - 2.The fulcrum of a uniform 20 Kg seesaw that is 4.0 m long is located 2.5 m from one end. A 30Kg child sits on the long end. The weight of a person sitting at the other end in order To balance the seesaw is ________ .
- A. 433 N
- B. 567 N
- C. 750 N
- D. 850 N
Answer: B. Textbook: Grade 10, unit 3 · section 3.5.2. - 3.A material rod that is 4.00 m long and $0.5\text{cm}^2$ in cross-sectional area is found to stretch 0.20cm under a tension of 5000N. The Young's Modulus for this material is _______.
- A. $2.0 \times 10^{11}\ \text{N/m}^2$
- B. $5.0 \times 10^8\ \text{N/m}^2$
- C. $1.0 \times 10^4\ \text{N/m}^2$
- D. $1.0 \times 10^8\ \text{N/m}^2$
Answer: A. Young’s modulus is the ratio of stress to strain. Use $Y=FL/(A\Delta L)$, with $A=0.5\,\mathrm{cm^2}=5.0\times10^{-5}\,\mathrm{m^2}$ and $\Delta L=0.20\,\mathrm{cm}=2.0\times10^{-3}\,\mathrm{m}$: $Y=(5000)(4.00)/[(5.0\times10^{-5})(2.0\times10^{-3})]=2.0\times10^{11}\,\mathrm{N/m^2}$. B, C, and D do not match this value. Textbook: Grade 10, unit 3 · section 3.4. - 4.Which one of the following is NOT true about Pascal's principle and its application?
- A. In pneumatic application, air is used for pressure transmission instead of liquid.
- B. The hydraulic lift is a speed multiplying device in which a large force lifts a light object over a long distance.
- C. It has applications in hydraulic brakes for vehicles, where confined oil connects a small piston (brake pedal) to a large piston connected to the brake drums on the wheel of the car.
- D. It has applications in hydraulic lift in which a small force is applied to a smaller piston is used to lift heavy object on large.
Answer: B. Pascal’s principle transmits pressure through a confined fluid. A hydraulic lift multiplies force, not speed, so B is not correct. A describes pressure transmission by air; C describes hydraulic brakes; D describes a small piston lifting a heavy object with a larger piston. Textbook: Grade 12, unit 3 · section 3.2. - 5.Which one of the following is NOT correct about factors that affecting the streamlining of objects moving in fluid?
- A. The mass of the object
- B. Shape and surface area of the object moving in fluid
- C. Compressibility of the fluid
- D. Density of the fluid
Answer: A. Fluid resistance depends on properties of the fluid and the object's shape and surface. The object's mass is not a factor that determines streamlining, so A is the choice that does not fit. B describes the object's shape and area; C describes fluid compressibility; D describes fluid density. Textbook: Grade 12, unit 3 · section 3.1. - 6.Which of the following is correct?
- A. Internal energy of a system is independent of its mass or the number of molecules in the system.
- B. Temperature is a measure of the average molecular kinetic energy of a gas.
- C. The temperature is a measure of the amount of energy that flows from hot to colder region.
- D. Heat is energy that can be transferred from one object to another at equal temperature.
Answer, explanation and textbook page: open in the app. - 7.Two moles of an ideal gas at a temperature of $308\,\text{K}$ is confined in a volume of $5.00 \times 10^{-3}\,\text{m}^3$. The pressure of the gas is (Universal gas constant $R= 8.314\,\text{J/mol.K}$).
- A. $1.23 \times 10^6\,\text{Pa}$
- B. $5.12 \times 10^6\,\text{Pa}$
- C. $1.02 \times 10^6\,\text{Pa}$
- D. $1.00 \times 10^6\,\text{Pa}$
Answer, explanation and textbook page: open in the app. - 8.A glass contains 12 mole of water molecule (H₂O). The number of water molecules, the mass of water, and the mass of each water molecules in the glass are, respectively (Molar mass of H is 1.0g and O is 16.0 g). 96.32 × 10 molecules 23 0.009 × 10 Kg −26 102 × 1023 molecules 6.02 × 10 Kg −26
- A. , 0.036 Kg,
- B. , 0.024Kg, . . 90.32 × 10 molecules 23 18 × 10 Kg −26 72.24 × 10 molecules 23 35.9 × 10 Kg −26
- C. , 0.192 Kg, .
- D. , 0.216 Kg, .
Answer, explanation and textbook page: open in the app.
Three resistors are connected across a battery as shown below. The potential difference across the resistors R1, R2, and R3 are, respectively, [Figure: A circuit diagram showing a DC voltage source labeled V = 110 V connected in series with a resistor labeled R₁ = 2 Ω on the upper rail. Following R₁, the circuit splits into two parallel branches: the first branch contains a resistor labeled R₂ = 3 Ω, and the second branch contains a resistor labeled R₃ = 6 Ω.
- 9.Both parallel branches connect back to the bottom rail returning to the negative terminal of the voltage source.]
- A. 110V, 25V, 30V
- B. 55V, 55V, 55V
- C. 55V, 82.5V, 165V
- D. 50V, 30V, 30V
Answer, explanation and textbook page: open in the app. - 10.According to Kirchhoff’s junction rule,
- A. The amount of electric charge entering a junction is equal to the amount leaving the junction.
- B. Charges can disappear or appear at the junction.
- C. The amount of electric charge flowing into a junction is less than the amount flowing out of the junction.
- D. The amount of electric charge flowing into a junction is greater than the amount flowing out of the junction.
Answer, explanation and textbook page: open in the app. - 11.Which of the following is true about galvanometer?
- A. A galvanometer can be converted to an ammeter that can read large currents by connecting a small resistance in parallel with it, and can be converted to a voltmeter by connecting a large resistance in series with the galvanometer
- B. To use a galvanometer as an ammeter that can read voltages, we connect a small resistance in series with the galvanometer
- C. Galvanometer can be converted to a voltmeter by connecting a small resistance in parallel with the galvanometer
- D. To use a galvanometer as an ammeter that can measure large currents, we need to measure its resistance by connecting a large resistance in series with the galvanometer.
Answer, explanation and textbook page: open in the app. - 12.According to the kinetic theory of gases, the
- A. Diffusion rate of a gas is inversely proportional to the square root of the molar mass because it is directly proportional to the molecular speed.
- B. Particles of an ideal gas undergo inelastic collision between themselves and with the walls of the container.
- C. Average translational kinetic energy of the particles of an ideal gas increases as gas gets cooled.
- D. Internal energy of an ideal gas is equal to the potential energy due to interaction between the particles of the gas.
Answer, explanation and textbook page: open in the app. - 13.At , an object undergoing SHM has maximum displacement of 0.650 m and angular frequency of 7.40 rad/s. Which of the following is correct about the motion of the oscillator?
- A. The frequency of the oscillator is 7.40 Hz and its period is 0.135 s. x = 0.65 cos(7.40t) a = −35.59 cos(7.40t)
- B. The position of the object is and its acceleration is .
- C. The position of the object is and acceleration is . x = 0.650 cos(7.40t) a = −3.59 sin(7.40t)
- D. The position of the object is and its velocity is . x = 0.650 sin(7.40t) V = 4.81 cos(7.40t)
Answer, explanation and textbook page: open in the app. - 15.Identify a true statement about a mechanical wave
- A. The speed of a wave traveling along a string increases as the tension in the string increases and as the linear density of the string decreases.
- B. The speed of a wave traveling across a thin string is equal to its speed when traveling across a thick string of the length and tension.
- C. The velocity of traveling wave is equal to the velocity of the particles through which the wave propagates.
- D. As a wave travels from one point too another along a medium, it transmits energy and particles of the medium from point to point.
Answer, explanation and textbook page: open in the app. - 16.Which one of the following is correct statements about the intensity of sound?
- A. It is inversely proportional to the square of the distance between from the source of sound.
- B. It is directly proportional to the square of the distance between from the source of sound.
- C. It is energy transmitted per unit time.
- D. It is the product of the a sound and area through which the sound is transmitted.
Answer, explanation and textbook page: open in the app. - 17.Which of the following is correct about Doppler effect?
- A. Doppler effect is the change in the frequency of a wave due to relative motion between the wave source and an observer.
- B. When a sound source moves away from stationary observer, the frequency detected by the observer increases, where as the wavelength decreases.
- C. When a source of sound wave moves toward stationary observer, the wavelength of the wave increases while its frequency decreases.
- D. It is the change in the velocity of a wave due to relative motion between the source of the wave and an observer.
Answer, explanation and textbook page: open in the app. - 18.Huygens's principle states that
- A. The secondary wavelets are parallel to the original wave front.
- B. All points along a wave front behave as a source of spherical secondary wavelets that have the same frequency and speed as the original wave front.
- C. The secondary wavelets combine to produce a new wave front which has a shape different from the original wave front.
- D. All points along a wave front acts as a source of plane secondary wavelets that travel at speeds and frequencies greater than that of the original wave.
Answer, explanation and textbook page: open in the app. - 19.Which one of the following is correct about the law of reflection and the law of refraction?
- A. The ratio of the sine incident angle to the sine of the refracted angle is equal to the ratio of the speed of incident wave to the speed of the refracted wave.
- B. If the speed of the incident wave is less than the speed of the refracted wave, the refracted wave bends towards the normal line.
- C. The speed and wave length of a reflected wave are different from that of an incident wave.
- D. The incident and refracted rays make equal angles with the boundary of the two interface.
Answer, explanation and textbook page: open in the app. - 20.Choose the correct statement about interference pattern due to diffraction of light through single and double slits.
- A. The light intensity of interference pattern due to double and single slits remain the same as the distance from the central bright fringe increases.
- B. The central bright fringes in both double and single slits interference are twice as wide as the first order bright fringes.
- C. Constructive interference due to double slit and single slit interference occur when the path difference between interfering waves is half-integer multiple of the wavelength.
- D. The bright and dark fringes formed when light passes through double slit have equal widths, where as the central bright fringe formed in single slit diffraction is twice wider as the first order maxima.
Answer, explanation and textbook page: open in the app. - 21.In order for interference of light waves to occur, the interfering light waves should
- A. Be incoherent.
- B. Be in phase.
- C. Have constant phase difference and the same frequency and speed.
- D. Be of different.
Answer, explanation and textbook page: open in the app. - 22.Which one of the following is true about fundamental forces?
- A. A weak nuclear force is an extremely short-range force that binds protons and neutrons together in a nucleus.
- B. Electromagnetic force is a long-range attractive force between particles due to their mass.
- C. Gravitational force is a long-range attractive force between particles due to their charge.
- D. Strong nuclear force is a short-range force that holds protons and neutrons to form atomic nucleus.
Answer, explanation and textbook page: open in the app.
Three blocks of mass , , and , placed on a horizontal frictionless table, are connected with strings and pulled to the right by a force F = 9N, as shown below. The acceleration a, tensions T1, and T2 are, respectively M 1 M 2 M 3 M 1 M 2 T 1 M 2 M 3 T 2 F M 3 [Figure: Three rectangular blocks labeled from left to right as , , and rest on a horizontal surface. A horizontal string connects to with tension labeled and arrows pointing inward. A second horizontal string connects to with tension labeled and arrows pointing inward.
- 23.A force labeled pulls block horizontally to the right with an arrow.] a = 2/3 m/s2 T = 1 2/3 N T = 2 2N a = 3/2 m/s2 T = 1 3/2 N T = 2 9/2 N
- A. , and .
- B. , and . a = 3/2 m/s2 T = 1 3N T = 2 9/2 N a = 3m/s2 T = 1 3N T = 2 9N
- C. , and .
- D. , and .
Answer, explanation and textbook page: open in the app. - 24.which of the following is correct about an astronaut inside an international space station orbiting the earth?
- A. The astronauts experiences weightlessness because the space station and the astronauts are freely falling towards the center of the earth.
- B. Because the earth exerts a larger force on the astronaut than on the space station, the astronaut experienced weightlessness.
- C. Since the earth exerts equal force on both the astronauts and the space, the astronaut experiences weightlessness.
- D. The astronauts experiences weightlessness since the earth's gravitational force on the astronaut is less than the earth's forces on the space station.
Answer, explanation and textbook page: open in the app. - 25.Two masses of $m_1$ and $m_2$ are balanced on a horizontal stick of negligible mass pivoted at the center of mass of the system. If the distance from $m_1$ to the center of mass is $3.0\text{m}$ and the distance from the mass $m_2$ to the center of mass is $1.0\text{m}$, the ratio of $m_1$ to $m_2$ ($m_1/m_2$) is?
- A. 3
- B. $1/3$
- C. $4/3$
- D. $3/4$
Answer, explanation and textbook page: open in the app. - 26.Identify the correct statement about energy, work, and force.
- A. Machines can multiply energy but not force.
- B. Energy cannot be possessed by an object at rest.
- C. Work is said to be done by a force whenever the force is exerted on an object.
- D. Force is a vector quantity, where as work and energy are scalars.
Answer, explanation and textbook page: open in the app. - 27.Distinguish between conservative and non-conservative forces.
- A. Friction force is an example of conservative force, whereas spring force and gravitational force are typical examples of non-conservative force.
- B. A conservative forces dissipates energy, where as non-conservative force does not.
- C. Work done by conservative force along any closed path is zero, whereas the work done by non- conservative force along a closed path is not zero.
- D. Work done by a conservative force is path dependent, whereas work done by non-conservative force does not depend on the path followed.
Answer, explanation and textbook page: open in the app. - 28.A crane raises $75.0\,\mathrm{Kg}$ of bricks from the ground to a height of $45.0\,\mathrm{m}$ in $52.0\,\mathrm{s}$ a constant speed. The average power of the crane is?
- A. 14.4 W
- B. 649 W
- C. 3,375 W
- D. 144 W
Answer, explanation and textbook page: open in the app. - 29.For a rigid body rotating about a fixed axis,
- A. For the same time interval, a point closer to the axis and a point father from the axis travel the same linear distance.
- B. For the same time interval, a point closer to the axis turn through a smaller angle than a point farther from the axis.
- C. A point closer to the axis has smaller linear speed than a point farther from the axis.
- D. A point closer to the axis has greater linear speed than a point father from the axis.
Answer, explanation and textbook page: open in the app. - 30.A disk of radius 0.10m and mass 0.1Kg is set into motion by a tangential force of 2.0 N applied at the edge of the 400 rad/s2 disk. If the angular acceleration of the disk is , the torque and angular velocity at 2.0 s are, respectively
- A. 0.5 Nm and 100 rad/s.
- B. 0.2 Nm and 800 rad/s.
- C. 0.2 Nm and 400 rad/s.
- D. 0.1 Nm and 200 rad/s.
Answer, explanation and textbook page: open in the app. - 31.Identify the correct statement about torque and angular momentum.
- A. No torque acts on an object when its angular momentum increases.
- B. The change in angular momentum is inversely proportional to the torque exerted for a given time interval.
- C. For the same time interval, a small torque and a large torque change angular momentum by the same amount.
- D. A small torque applied for a longer time and a large torque exerted for a shorter time have the same effect on the change of angular momentum.
Answer, explanation and textbook page: open in the app. - 32.A scientific method
- A. Is a scientific procedure where a researcher first predicts the result of a problem before proposing the possible hypothesis.
- B. Begins from an accepted scientific theory and concludes with designing an experiment.
- C. Is a scientific procedure which ensures a rigorous evidence-based structure in which only ideas that have been carefully tested are accepted as scientific theory.
- D. Is scientific procedure in which a researcher begins with performing experiments.
Answer, explanation and textbook page: open in the app. - 33.Which one of the following is correct about accuracy and precision of a measurement?
- A. Accuracy is related to the number of significant figures, whereas precision describes how well we minimizes random errors.
- B. A more accurate measurement has larger uncertainty, whereas a more precise data has smaller uncertainty.
- C. Accuracy describes the closeness of repeatedly measured data to each other, whereas precision describes about the closeness of a data to a true value.
- D. Accuracy refers to the closeness of repeatedly measured data to a true value, whereas precision is related to the closeness of the measured data to each other.
Answer, explanation and textbook page: open in the app. - 34.In an experiment to measure the velocity of a ball rolling along x-axis, a student recorded the distance traveled and time taken by the ball. Which of the following data represent constant velocity of the ball?
- A. x(m)045679
- B. x(m)0246810 t(s) 01 2344 t(s) 01 2345
- C. x(m)03569
- D. x(m)023467 t(s) 01 235 t(s) 01 2234
Answer, explanation and textbook page: open in the app. - 35.A position vector of an object
- A. Is independent of the origin from which it is measured.
- B. Is a measure of how fast it is moving relative to stationary reference frame.
- C. Describes its distance from a point in a specified direction.
- D. Describes its distance from a given point in all directions.
Answer, explanation and textbook page: open in the app. - 36.Consider two force vectors in x-y plane: F1 = 10N making a angle above the horizontal and F2 = 20 N 60∘ making a angle above the horizontal. Which of the following is true? 45∘
- A. The direction of their resultant vector is above the horizontal.
- B. The magnitude of their resultant is 42 N.
- C. The horizontal and vertical components of their resultant are 18.66N and 22.32N, respectively.
- D. The horizontal and vertical components of their resultant are 15N and 26N, respectively.
Answer, explanation and textbook page: open in the app. - 37.Given four vectors , , , , which pair of theses vectors are collinear?
- A. C and D
- B. A and B
- C. B and C
- D. A and C
Answer, explanation and textbook page: open in the app. - 38.While going to school, a student travels 3km, East and then 4km, North in 2 hrs. the magnitude of student's average velocity and average speed are, respectively
- A. 2.5 km/hr and 3.5km/hr.
- B. 2km/hr and 7km/hr/.
- C. 5km/hr and 7km/hr.
- D. 3.5km/hr and 2.5km/hr.
Answer, explanation and textbook page: open in the app. - 39.A boy throws a ball vertically upward with an initial speed of 20 m/s. Neglecting air resistance, which of the following is true about the motion of the?
- A. The time taken to reach the maximum height is 4s.
- B. Its velocity after 3s is 50m/s, downward.
- C. Its maximum height is 20m.
- D. Its velocity after 1s is 30 m/s, upward.
Answer, explanation and textbook page: open in the app. - 40.Choose a correct statement about centripetal force and centripetal; acceleration.
- A. For an object moving in a circular path, its centripetal force and centripetal acceleration are parallel and directed toward the centre of the path.
- B. Centripetal acceleration and centripetal force are constant in direction, but vary in magnitude.
- C. Centripetal force on an object moving in a circular path is perpendicular to the radius of the path.
- D. Centripetal force on an object moving in a circular path tends to pull the object outward from its path.
Answer, explanation and textbook page: open in the app. - 41.According to Newton's law of Universal Gravitation,
- A. The speed of a satellite moving around the Earth in a circular orbit depends on the mass of the satellite.
- B. For two interacting objects, gravitational force exerted on a light object is less than the force on the heavy one.
- C. The period of a satellite orbiting the Earth in a circular orbit increases as the radius of its orbit increases.
- D. The gravitational attraction between two objects is directly proportional to the square of the distance between them.
Answer, explanation and textbook page: open in the app.