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Grade 12 Physics national exam, 2006 E.C. (2014 G.C.)
43 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.The distance between two point charges is doubled. What will happen to the force of interaction between the charges?
- A. The force will be doubled.
- B. The force will be reduced by half.
- C. The force will be reduced by a factor of ᓸ.
- D. The force will not be affected.
Answer: C. The force between point charges follows an inverse-square rule: it decreases with the square of the distance. Doubling the distance gives $F/2^2=F/4$, so the force is reduced by a factor of $4$. A is wrong because the force does not double. B is wrong because it is reduced to one quarter, not one half; D is wrong because distance affects the force. Textbook: Grade 11, unit 4 · section 4.1. - 2.What does the slope of a velocity time graph represent?
- A. distance
- B. acceleration
- C. displacement
- D. speed
Answer: B. The key idea is that the slope of a velocity–time graph gives acceleration. Slope is change in velocity divided by change in time, which is acceleration. A is wrong because distance is not the slope; C is wrong because displacement is the area under the graph; D is wrong because speed is a velocity value, not its rate of change. Textbook: Grade 11, unit 3 · section 3.3. - 4.A transverse sinusoidal wave is traveling on a string. Which statement is correct about a point on the string?
- A. The point moves in the same direction as the wave.
- B. The point moves in simple harmonic motion with a different frequency than that of the wave.
- C. The point moves in simple harmonic motion with the same angular frequency as the wave.
- D. The point moves in uniform circular motion with a different angular speed than the wave.
Answer: C. A point on a string in a sinusoidal wave moves up and down in simple harmonic motion. Option C is correct because that motion has the same angular frequency as the wave. Option A is wrong because the point moves across the string, not along the wave. Option B gives the wrong frequency, and option D describes circular rather than oscillating motion. Textbook: Grade 11, unit 3 · section 3.5. - 5.Two none zero vectors $D$ and $E$ have precisely equal magnitudes. For the magnitude of $D+E$ to be 3 times larger than the magnitude of $D-E$, what must be the angle between $D$ and $E$?
- A. 30°
- B. 37°
- C. 53°
- D. 60°
Answer: D. Textbook: Grade 11, unit 2 · section 2.4. - 6.Which statement is correct about the pressure under a fluid in a container?
- A. It depends on the volume of the fluid.
- B. It depends on the density of the fluid.
- C. It depends on the shape of the container.
- D. It is independent of the depth of the fluid.
Answer: B. The key idea is that pressure in a still fluid depends on its density and depth. The relation is $p=\rho gh$, so pressure increases with fluid density when depth and gravity stay the same. A is wrong because volume alone does not set the pressure; C is wrong because container shape does not set it; D is wrong because pressure does depend on depth. Textbook: Grade 12, unit 3 · section 3.2. - 7.A capacitor made of parallel plates is charged by connecting it to a battery. The distance between the plates is much less than the surface area of each plate. After fully charged if the plates are disconnected from the battery and then pulled apart a little, what will happen to the total stored energy, the electric field, and the potential difference between the plates?
- A. The electric field between the plates increase.
- B. The potential difference between the plates remain the same.
- C. The total energy stored in the capacitor increase.
- D. The electric field, the potential difference and the stored energy remain the same.
Answer, explanation and textbook page: open in the app. - 8.Which one of the following statements is true about the motion of a particle in a circular path?
- A. The centripetal acceleration is constant if the particle?s speed is constant.
- B. The tangential acceleration can be perpendicular to the velocity vector of the particle.
- C. The centripetal acceleration is always in the direction perpendicular to the velocity vector of the particle.
- D. The acceleration is always perpendicular to the velocity vector of the particle.
Answer, explanation and textbook page: open in the app.
Two rectangular loops of wire lie in the plane of this paper as shown in the figure below, if the current I in the outer loop is counter clockwise and increases with time, which one of the following statements is correct about the current induced in the inner loop? [Figure: A line drawing of two concentric rectangles drawn in the plane of the page: a larger outer rectangle and, centred inside it, a smaller inner rectangle. Immediately to the right of the outer rectangle's right-hand side there is a straight vertical line carrying a solid arrowhead at its top, pointing upward, indicating that the current in the outer loop runs upward along that right-hand side (i.e. counter clockwise around the outer loop).
- 9.No numeric labels appear on the figure; the current symbol I is named only in the stem.]
- A. A current is induced in the inner loop in the clockwise direction.
- B. A current is induced in the inner loop in the counter wise direction.
- C. The induced current in the inner loop creates a magnetic field inside the area bounded by the inner loop in the same direction of the magnetic field that the outer loop produces in this same area.
- D. It is zero.
Answer, explanation and textbook page: open in the app. - 10.Two men, A and B, are loading identical boxes onto a truck. A lifts his box staring up from the ground to the bed of the truck, whereas B slides his box up a rough ramp to the truck, which statement is correct about the change in the potential energy on the box earth system?
- A. A and B change the potential energy by the same amount.
- B. A changes more potential energy than B.
- C. B changes more potential energy than A.
- D. None of those statements is necessarily true because the force of friction and the angle of the incline is unknown.
Answer, explanation and textbook page: open in the app. - 11.Two projectiles are fired from ground level at equal speed but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. The projectile to hit the ground first will be the one fired at (neglect air resistance)
- A. 60 degrees
- B. 30 degrees
- C. both hit at the same time
- D. cannot be determined from the given condition.
Answer, explanation and textbook page: open in the app. - 13.A small radio receiver uses a battery that delivers a constant current of 25mA for 3 hours. Calculate the total charge delivered by the battery.
- A. 1080000C
- B. 270000
- C. 540C
- D. 270C
Answer, explanation and textbook page: open in the app. - 14.A cup of coffee at a temperature of 80°C is placed on table in a 20°C room. What happens to the thermal energy and molecular motion of the coffee when it is left on the table?
- A. The thermal energy decreases and the molecules move more slowly.
- B. The thermal energy increases and the molecules move more slowly.
- C. The thermal energy decreases and the molecules move faster.
- D. The thermal energy increases and the molecules move faster.
Answer, explanation and textbook page: open in the app. - 15.The vector is perpendicular to if is equal to
- A. -2
- B. -1
- C. 2
- D. 3
Answer, explanation and textbook page: open in the app. - 18.A hoop of mass $M$ and radius $R$ is at rest at the top of an incline plane of height $h$. the hoop rolls down the plane without slipping. When the hoop reaches bottom, its angular momentum about its center of mass is:
- A. $Mgh$
- B. $MR\sqrt{2gh}$
- C. $MR\sqrt{\frac{gh}{2}}$
- D. $MR\sqrt{gh}$
Answer, explanation and textbook page: open in the app. - 19.What is the resistance of a copper cable if it has a cross sectional area of $1\,\text{cm}^2$ and a length of $2\,\text{km}$? The resistivity of copper is $2\times10^{-8}\,\Omega\text{m}$.
- A. $0.0004\,\Omega$
- B. $0.004\,\Omega$
- C. $0.04\,\Omega$
- D. $0.4\,\Omega$
Answer, explanation and textbook page: open in the app. - 20.When a load of 500kg is hanging from a steel wire of length 3m and cross sectional area , the wire Y = 2 × 1011 stretches beyond its no load length. If the Youngᓼs modulus for the wire made of steel is Pa, what is the change in length of the wire beyond its no load length?
- A. 3.75mm
- B. 2.75mm
- C. 1.75mm
- D. 0.75
Answer, explanation and textbook page: open in the app.
As shown in Figure below, two blocks are connected by a string of negligible mass passing over a pulley of radius r = 0.2m and moment of inertia I. The block on the frictionless incline is moving with a constant a = 2.0m/s2 acceleration up along the incline. What is the moment of inertia of the pulley? [Figure: A hand-drawn right-triangular wedge sitting on horizontal ground, with the right angle at the bottom right; the sloping face rises from the lower left to the apex at the top right, and the angle between the slope and 370 the ground is marked with an arc labelled . A square block labelled 15kg rests on the sloping face.
- 21.A string T 1 leaves the top of that block, runs up the slope parallel to the incline (labelled above it), passes over a circular T 2 m pulley drawn at the apex of the wedge, and then hangs vertically down the right-hand vertical face (labelled to the right of it) to a square block labelled , with '20kg' printed to the right of that block.] 2 0.8kgm2 1.25kgm2
- B. 4kgm2 40kgm2
Answer, explanation and textbook page: open in the app. - 22.A viewing screen is separated from a double slit by 4.80m. The distance between the two slits is 0.030mm. Monochromatic light is directed toward the double slit and forms and interference pattern on the screen. The first dark fringe is 4.50 cm from the center line on the screen. What is the wavelength of the light?
- A. 1250nm
- B. 7200nm
- C. 2500nm
- D. 5625nm
Answer, explanation and textbook page: open in the app. - 23.A horizontal pipe of 10cm in diameter has a smooth reduction to a pipe of 5cm in diameter. If the pressure of the water in the larger pipe is 80kPa and the pressure in the smaller pipe is 6kPa, at what rate does the water flow through the smaller pipe?
- A. 1.63m/s
- B. 6.53m/s
- C. 13.6m/s
- D. 42.67m/s
Answer, explanation and textbook page: open in the app.
An aluminium block of mass and a copper block of mass are connected by a light string θ = 53∘ over a frictionless pulley. They sit on a steel surface as shown in figure below , where . The coefficient of kinetic friction between the steel surface and each block in 0.3. if the blocks are released from rest what is the tension T in the string? [Figure: A hand-drawn steel block shaped like a wedge with a flat horizontal top on the left and a face sloping m 1 m down to the right; the word 'Steel' is printed inside the body. A rectangular block labelled sits on the flat horizontal top surface. A string runs horizontally to the right from , passes over a small circular pulley mounted at the top corner where the horizontal surface meets the sloping face, then runs down along the 1 m 2 sloping face to a square block labelled resting on that slope. At the bottom of the slope, an arc marks the θ angle between the sloping face and the horizontal, labelled .
- 24.No numeric values appear on the drawing itself.]
- A. 29.40N
- B. 17.25N
- C. 12.25N
- D. 8.60N
Answer, explanation and textbook page: open in the app.
An object of mass 3kg hangs from three light inextensible wires as shown in figure below. Two of the wires θ = 1 53∘ θ = 2 37∘ make angles and with the horizontal. If the system is in equilibrium, what will be the T 1 T 2 tensions and in the wires? [Figure: A hand-drawn figure showing a horizontal ceiling at the top, drawn as a straight line with hatching strokes above it. Two wires run down from the ceiling and meet at a common knot below and between them, θ 1 T 1 θ 2 T2 forming a V. The left wire makes an angle with the ceiling marked by an arc labelled , and the wire itself is labelled below and to the left. The right wire makes an angle with the ceiling marked by an arc labelled , and that wire is labelled below and to the right. From the knot a third, vertical wire runs straight down to a solid rectangular block, and a short vertical arrow points downward from the bottom of the block (its weight).
- 25.No numeric values are written on the drawing.] T = 1 18N T = 2 24N T = 1 T = 2 18N
- A. and
- D. and T = 1 T = 2 24N T = 1 24N T = 2 18N
Answer, explanation and textbook page: open in the app. - 26.An object of mass $m$ is hung from a spring and set into oscillation. The frequency of the oscillation is measured and recorded as $f$. if the object of mass $m$ is replaced with an object of mass $m$ is replaced with an object of mass $2m$ and set into oscillation, what will be the frequency of the motion?
- A. $f/\sqrt{2}$
- B. $f$
- C. $(\sqrt{2})f$
- D. $2f$
Answer, explanation and textbook page: open in the app. - 27.A placekicker must kick a football from a point which is at a distance of 36.0 m from the goal. When kicked, the 37∘ ball leaves the ground with a speed of 20.0m/s at an angle of to the horizontal. If the ball hits the crossbar of the goal at a height h and bounces back what will be the height of the crossbar?
- A. 2.45m
- B. 2.85
- C. 3.00m
- D. 3.15m
Answer, explanation and textbook page: open in the app. - 28.A body moving with constant acceleration covers the distance between two points $60\text{m}$ apart in $5\text{s}$. Its velocity as it passes the second point is $15\text{m/s}$. what is the acceleration?
- A. $3\text{m/s}^2$
- B. $2.4\text{m/s}^2$
- C. $1.8\text{m/s}^2$
- D. $1.2\text{m/s}^2$
Answer, explanation and textbook page: open in the app. - 29.Which of the following combinations of properties would be most desirable for a heat sink in a machine?
- A. high specific heat and low conductivity.
- B. low heat specific heat and low conductivity.
- C. high specific heat and high conductivity.
- D. low specific heat and low conductivity.
Answer, explanation and textbook page: open in the app. - 30.A 6V battery is connected across the primary coil of a transformer having 50 turns. If the secondary coil of the transformer has 100 turns, what voltage appears across the secondary?
- A. 24.0V
- B. 12.0V
- C. 6.00V
- D. 3.00V
Answer, explanation and textbook page: open in the app. - 31.The change in entropy is zero for:
- A. reversible isobaric processes.
- B. reversible adiabatic processes.
- C. reversible isothermal processes.
- D. reversible processes during which no work is done.
Answer, explanation and textbook page: open in the app. - 32.Two particles with masses 2m and 3m are moving toward each other along the x axis with the same initial speed v. Particle 2m is traveling to the left, and particle 3m is traveling to the right. They undergo an elation glancing collision such that particle 2m is moving in the negative y direction after the collision. What are the x component of the final velocity of particle 3m and the kinetic energy of particle 2m, respectively? 0.7mV 2 1.41mV 2
- A. 0.33v and
- B. 0.33v and 0.71mV 2 1.4mV 2
- C. 0.67v and
- D. 0.67v and
Answer, explanation and textbook page: open in the app. - 33.Two separate coherent sources produce waves whose wavelengths are 0.10m. which statement is correct about points that are 3.2m away from one source?
- A. constructive interference occurs if the points are 3.0m from the other source
- B. constructive interference occurs if the points are 3.05m from the other source.
- C. constructive interference occurs if the points are 2.95m from the other source.
- D. destructive interference occurs if the points are 3.2m from the other source.
Answer, explanation and textbook page: open in the app. - 34.A coil formed by wrapping 50 turns of wire in the shape of a square is positioned in a magnetic field so that the 37∘ normal to the plane of the coil makes an angle with the direction of the field. When the magnetic field is increased uniformly from 200 mT to 600mT in 4.00s, an emf of magnitude 160.0 mv is induced in the coil. What is the total length of the wire in the coil?
- A. 100m
- B. 200m
- C. 300m
- D. 400m
Answer, explanation and textbook page: open in the app. - 35.The half-life of radium 224 is 3.5 days. What fraction of the sample remains undecided after fourteen days? (if needed use $\ln 2 = -\ln(1/2) \approx 0.693$)
- A. ?
- B. �
- C. $1/8$
- D. $1/16$
Answer, explanation and textbook page: open in the app.
Two positive charges of magnitude q are each a distance d from the origin A of a coordinate system as shown below. The magnitude of the electric field is minimum at point [Figure: A hand-drawn coordinate diagram. A horizontal axis runs across the figure with an arrowhead at the right end labelled X; a vertical axis rises from the origin with an arrowhead at the top labelled Y, and the origin itself is marked with a solid dot (this is point A named in the stem). Two small open circles sit on the horizontal axis, each labelled +q above it: one a distance d to the left of the origin and one a distance d to the right of the origin. The two spacings are marked underneath the axis by short dashed segments each labelled d. Further to the right along the horizontal axis there are two solid dots: the nearer one labelled B (above it) and the farther one labelled C (above it), with '3d' printed just below the point C.
- 36.Below the axis, dashed vertical lines drop from each of the two +q charges to a dashed horizontal line, forming an open rectangle; the lower-left corner of that dashed rectangle is a solid dot labelled D and the lower-right corner is a solid dot labelled E.]
- A. A
- B. B
- C. C
- D. D
Answer, explanation and textbook page: open in the app. - 37.If the terminals of a battery with zero internal resistance are connected across two identical resistors in series, the total power delivered by the battery is 8 W. if the same is connected across the same resistors in parallel, what is the total power delivered by the battery?
- A. 2W
- B. 4W
- C. 16W
- D. 32W
Answer, explanation and textbook page: open in the app. - 38.Wire B has twice the length and twice the radius wire A. Both wires are made from the same material. If wire A has a resistance R, what is the resistance of wire B?
- A. 4R
- B. 2R
- C. R/2
- D. R/4
Answer, explanation and textbook page: open in the app. - 39.The sound level at a distance of 4.00m from a source is 120dB. At what distance is the sound level 100dB?
- A. 0.40m
- B. 4.80m
- C. 40m
- D. 48m
Answer, explanation and textbook page: open in the app. - 40.An ideal gas is at a temperature of 300k. if we wish to double the root mean square (rms) speed of the molecules of the gas, to what value must we raise its temperature?
- A. 450K
- B. 600k
- C. 800k
- D. 1200k
Answer, explanation and textbook page: open in the app. - 41.Suppose that the index of refraction of a soap bubble film is 1.25, what is the minimum thickness of the soap-bubble film that results in constructive interference in the reflected light if the film is illuminated with light whose wavelength in free space is $\lambda = 600\,\text{nm}$?
- A. 120nm
- B. 150nm
- C. 300nm
- D. 450nm
Answer, explanation and textbook page: open in the app. - 42.A wire carries a steady current of 2.4A. A straight section of the wire is 0.75m long and lies in xy-plane along the x-axis within a uniform magnetic field, B=1.6kT. If the current is in the positive x direction, what is the magnetic force on the section of wire?
- A. 2.88N, in the negative y direction.
- B. 2.88N, in the positive y direction.
- C. 3.84N, in the negative y direction.
- D. 3.84N, in the positive y direction.
Answer, explanation and textbook page: open in the app. - 43.Two different capacitors of capacitance and are connected in series across a 120V supply line. The charged capacitors are disconnected from the line and from each other, and reconnected with C 1 C terminals of like sign together. What will be the final charges on and respectively? 2
- A. and
- B. and 57.63μC 86.4μC 115.2μC 127.8μC 144μC 288μC
- C. across each
- D. across each
Answer, explanation and textbook page: open in the app. - 44.A glass flask whose volume is exactly $1{,}000\,\text{cm}^3$ at $0^\circ\text{C}$ is totally filled with $1000\,\text{cm}^3$ of mercury at this temperature. When flask and mercury are heated to $100^\circ\text{C}$, $15.2\,\text{cm}^3$ of mercury overflow. If the coefficient of volume expansion of mercury is $1.82\times10^{-4}$ per Celsius degree, what should be the coefficient of volume expansion of the glass?
- A. $1.52\times10^{-4}/\mathrm{C}^\circ$
- B. $1.82\times10^{-4}/\mathrm{C}^\circ$
- C. $3.00\times10^{-4}/\mathrm{C}^\circ$
- D. $1.00\times10^{-5}/\mathrm{C}^\circ$
Answer, explanation and textbook page: open in the app. - 45.A heat engine is being designed to have a Carnot efficiency of 65.0% when operating between two energy 20.0 C ∘ reservoirs. If the temperature of the cold reservoir is , what must be the temperature of the hot reservoir?
- A. 570C
- B. 3100C
- C. 5640C
- D. 8070C
Answer, explanation and textbook page: open in the app. - 47.A 10.0m uniform ladder weighing 200N rests against a frictionless wall. The ladder makes angles with the horizontal, if the ladder is just on the verge of slipping when a 600.0N firefighter is 6.00m along the ladder from the bottom, what is the coefficient of static friction between the ladder and ground?
- A. 0.3240
- B. 0.4313
- C. 0.5750
- D. 0.7667
Answer, explanation and textbook page: open in the app. - 48.A block of mass 1.6kg is attached to a horizontal spring that has a force constant of 200N/m. The spring is compressed 2.0cm and is then released from rest. At what speed will the block pass through the equilibrium position if a constant friction force of 10.0N retards its motion from the moment it is released?
- A. 75m/s
- B. 50m/s
- C. 70m/s
- D. 55m/s
Answer, explanation and textbook page: open in the app.