NATIONAL SENIOR CERTIFICATE GRADE 12

Transcription

1 NATIONAL SENIOR CERTIFICATE GRADE 1 PHYSICAL SCIENCES: PHYSICS (P1) ADDITIONAL EXEMPLAR 008 MARKS: 150 TIME: 3 hours This question paper consists of 14 pages, 3 data sheets and 1 answer sheet.

2 Physical Sciences/P1 DoE/Additional Exemplar 008 INSTRUCTIONS AND INFORMATION Write your examination number (and centre number if applicable) in the appropriate spaces on the ANSWER SHEET and ANSWER BOOK. Answer ALL the questions. Answer SECTION A on the attached ANSWER SHEET. Answer SECTION B in the ANSWER BOOK. Non-programmable calculators may be used. Appropriate mathematical instruments may be used. Number the answers correctly according to the numbering system used in this question paper. Data sheets are attached for your use. Give brief motivations, discussions, et cetera where required.

3 Physical Sciences/P1 3 DoE/Additional Exemplar 008 SECTION A Answer this section on the attached ANSWER SHEET. QUESTION 1: ONE-WORD ITEMS Give ONE word/term for each of the following descriptions. Write only the word/term next to the question number ( ) on the attached ANSWER SHEET The product of the magnitude of a force on an object and the magnitude of the distance that the object moves in the direction of the force The rate at which work is done The pattern observed on a screen when red light passes through a double slit Force per unit charge The process by which an atom moves to its ground state emitting a photon of energy without any outside influence (1) (1) (1) (1) (1) [5] QUESTION : MATCHING ITEMS Choose an item from COLUMN B that matches a description in COLUMN A. Write only the letter (A J) next to the question number (.1.5) on the attached ANSWER SHEET..1 COLUMN A The product of force and velocity A COLUMN B potential dividers. Complementary colours B impulse.3 The colour model used to produce colour on a television screen C D subtractive cyan light and green light.4 Resistors in series E power.5 The condition in a laser where more atoms are in the excited state than in the ground state F G population inversion current dividers H additive I stimulated emission J blue light and yellow light [5]

4 Physical Sciences/P1 4 DoE/Additional Exemplar 008 QUESTION 3: TRUE/FALSE ITEMS Indicate whether the following statements are TRUE or FALSE. Choose the answer and write 'true' or 'false' next to the question number ( ) on the attached ANSWER SHEET. Correct the statement if it is FALSE A long cannon will impart a greater impulse to a cannonball than a short cannon because the force acts over a longer time. The light bands produced by red light through a double slit is narrower than the bands produced by blue light. Halving the distance between two stationary charges doubles the electrostatic force that the charges exert on each other. A DC generator produces a constant direct current similar to that produced by a battery. Laser light is coherent, monochromatic, sharply focussed and highly directional. () () () () () [10]

5 Physical Sciences/P1 5 DoE/Additional Exemplar 008 QUESTION 4: MULTIPLE-CHOICE QUESTIONS Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and make a cross (X) in the block (A D) next to the question number ( ) on the attached ANSWER SHEET. 4.1 A boy, mass m, and a girl, mass m, are facing each other on roller skates. With their hands, they push off against one another. The boy experiences a force F and an acceleration a to the left. Which ONE of the following best describes the magnitudes of the force and acceleration experienced by the girl? Ignore the effects of friction. FORCE ACCELERATION A 1 F a B F a C D F F 1 a 1 a (3)

6 Physical Sciences/P1 6 DoE/Additional Exemplar A stone is dropped from the edge of a cliff. Which ONE of the following graphs best represents the change in kinetic energy of the stone during its fall? A E k B E k C E k t(s) D E k t(s) t(s) t(s) (3) 4.3 A circus clown wears a yellow jacket and a red nose. Which ONE of the following correctly describes the colour of the jacket and the nose of the clown when illuminated with cyan light? JACKET NOSE A blue red B green black C cyan black D green cyan (3)

7 Physical Sciences/P1 7 DoE/Additional Exemplar A battery with emf ε and internal resistance r is connected to a resistor R as shown in the circuit diagram below. R V A ε r A second resistor of the SAME RESISTANCE is now connected in parallel with resistor R. How will the voltmeter and ammeter readings change when the second resistor is connected in the circuit? VOLTMETER READING AMMETER READING A stays the same decreases B increases stays the same C decreases increases D increases increases (3) 4.5 The energy level diagram for an element is shown below. E 0 represents the ground state. The energy change from E 0 to E 1 is smaller than that for E to E 1. E E 1 The electron transition from E to E 1 corresponds to a green line in the element's spectrum. The transition E 0 to E 1 corresponds to... E 0 A B C D absorption of green light. emission of green light. emission of red light. absorption of red light. (3) [15] TOTAL SECTION A: 35

8 Physical Sciences/P1 8 DoE/Additional Exemplar 008 SECTION B INSTRUCTIONS AND INFORMATION Answer SECTION B in the ANSWER BOOK. The formulae and substitutions must be shown in ALL calculations. Round off your answers to TWO decimal places where applicable. QUESTION 5 Any falling object which is being acted upon only by the force of gravity is said to be in a state of free fall. 5.1 Briefly describe how you can make use of a small free-falling stone to determine how deep the water level is in a well (represented by y in the diagram below). y water (3) 5. Give ONE reason why the concept of free fall might not give a correct answer. (1) 5.3 A student is at the top of a building of height h. He throws a stone, X, upward with a speed v. He then throws a second identical stone, Y, downward at the same speed v Redraw the following set of axes in the ANSWER BOOK and sketch the graphs of position versus time for each of the stones X and Y. Use the ground as the point of zero position. Position (m) t(s) (4) 5.3. How will the velocities of the two stones, X and Y, compare when they reach the ground? Explain your answer. (4)

9 Physical Sciences/P1 9 DoE/Additional Exemplar A mountain climber stands at the top of a 50 m cliff that overhangs a calm pool. She throws two stones vertically downward 1 s apart and observes that the two stones reach the water simultaneously after a while. The first stone was thrown at an initial speed of m s -1. QUESTION 6 Calculate the initial speed at which she threw the second stone. Ignore the effects of friction. (6) [18] New cars have a crumple zone to help minimise injuries during accidents. In addition seat belts, air bags and padded interiors can reduce the chance of death or serious injury. 6.1 Use principles in Physics to explain how air bags can reduce the chance of death or injury. (3) 6. In a crash test, a car of mass 1, x 10 3 kg collides with a wall and rebounds as illustrated below. The initial and final velocities of the car are 1 m s -1 to the left and m s -1 to the right respectively. The collision lasts 0,1 s. 1 m s -1 m s -1 Calculate the: Impulse of the car during the accident Average force exerted on the car (4) (3) 6.3 How will the magnitude of the force exerted on the car be affected if the time interval of the collision remains 0,1 s, but the car does not bounce off the wall? Write down only INCREASES, DECREASES or REMAINS THE SAME. Explain your answer. () [1]

10 Physical Sciences/P1 10 DoE/Additional Exemplar 008 QUESTION 7 A gymnast jumps vertically upward from a trampoline as illustrated below. v i 1,3 m 5 m The gymnast leaves the trampoline at a height of 1,3 m and reaches a maximum height of 5 m. Ignore the effects of friction. 7.1 Write down the work-energy theorem. () 7. Use energy principles to calculate the initial speed v i with which the gymnast leaves the trampoline. (5) [7] QUESTION 8 The sketch below shows a stationary ambulance. The siren of the ambulance emits sound waves of frequency 700 Hz. The driver of a car approaching the ambulance and passing it at constant speed, observes the frequency of the emitted sound waves to change by 80 Hz. 700 Hz Stationary ambulance Car passing at constant speed 8.1 Name and state the wave phenomenon illustrated above. (3) 8. Take the speed of sound in air as 340 m s -1 and calculate the speed at which the car passes the ambulance. (5) [8]

11 Physical Sciences/P1 11 DoE/Additional Exemplar 008 QUESTION 9 During a demonstration of a wave phenomenon, monochromatic red light passes through a slit of width 1,8 x 10-4 m and shines on a flat screen a distance of 0,4 m away from the slit. The wavelength of the light is 675 nm. screen θ θ 0,4 m First dark band y Midpoint of central bright band y First dark band 9.1 Name the phenomenon demonstrated above. (1) 9. Briefly explain how the dark bands in the observed pattern are formed. () 9.3 Calculate the width y of the central bright band. (6) 9.4 How will your answer to QUESTION 9.3 change if the width of the slit is changed to 1,8 x 10-6 m? Write only INCREASES, DECREASES or REMAINS THE SAME. Give a reason for your choice. (3) 9.5 The red light incident on the slit now passes through a yellow filter and then through a magenta filter before reaching the slit. What colour will now be observed for the central bright band? Explain your answer. (3) [15]

12 Physical Sciences/P1 1 DoE/Additional Exemplar 008 QUESTION 10 A capacitor's function is to store charge or electrical energy. Capacitors also function as filters, passing alternating current (AC) and blocking direct current (DC) Briefly explain how a capacitor can block direct current (DC). () 10. You are requested to design a parallel plate capacitor with a capacitance of 00 pf using the following materials: Two connecting wires A whole sheet of aluminium foil of area 0, m Use the following steps as guidance in your design: Calculate the distance between the plates of the capacitor. Make a sketch of your design and indicate the dimensions of the capacitor on the sketch. What change will you make to your design, still using all the supplied materials, to change the capacitance of the capacitor to 100 pf? (4) (4) (1) 10.3 Supercapacitors (capacitors of 1 farad and more) are well suited to replace batteries in many applications. This is because their scale is comparable to that of batteries at the moment, from small ones used in cellular phones to large ones that can be found in cars. Even though supercapacitors have a lower energy density compared to batteries, they avoid many of the disadvantages of batteries Compare the way in which capacitors and batteries store energy. Name ONE disadvantage of batteries when disposed of in the environment. The following statement appears in an advertisement of a certain type of battery: 'Capacitors cannot function without batteries they need a source of energy. On the other hand, batteries don t need capacitors.' Briefly explain why this is a valid statement. () (1) () [16]

13 Physical Sciences/P1 13 DoE/Additional Exemplar 008 QUESTION 11 Four resistors of different resistances are connected in a circuit as shown below. The battery has an emf of 30 V and an internal resistance of Ω. The resistance of the connecting wires is negligible. 6 Ω X 4 Ω 6 Ω Y 10 Ω ε = 30 V Ω 11.1 Define the concept emf of a battery. () 11. Calculate the potential difference between points X and Y. (7) [9] QUESTION 1 The average power of a lamp is 15 W. The lamp can be used with either an AC supply or a DC supply. The graph below shows the AC potential difference. potential difference (V) 1-1 time (s) 1.1 Calculate the potential difference of a DC supply that will produce the same brightness of the lamp. (3) 1. Calculate the peak current through the lamp when connected to a 1 V AC supply. (4) 1.3 Draw a sketch graph of current through the lamp against time when connected to the AC supply. Indicate the value of the peak current on the graph. (3) [10]

14 Physical Sciences/P1 14 DoE/Additional Exemplar 008 QUESTION 13 The diagram below shows a basic electric generator. N S What type of generator (AC or DC) is illustrated above? Give a reason for your answer. Is the induced potential difference in the coil illustrated above about to increase or to decrease? Refer to the change in magnetic flux as the loop rotates from the vertical to the horizontal position, and explain your answer. State ONE change that can be made to the above generator to increase the output potential difference. () (5) (1) [8] QUESTION 14 A learner wants to demonstrate the photoelectric effect. He uses a disk of zinc placed on an electroscope. The work function of zinc is 6,9 x J Define the concept work function. () 14. Calculate the maximum wavelength of light that will eject electrons from the zinc. (4) 14.3 The electroscope is negatively charged and then exposed to ultraviolet light from a mercury discharge lamp. One of the wavelengths of the light is 60 nm. Calculate the kinetic energy of an electron emitted from the zinc disk by a photon of this light. (4) 14.4 When the student attempts the experiment with a positively charged electroscope, he finds that the ultraviolet light has no apparent effect. Explain this observation. () [1] TOTAL SECTION B: GRAND TOTAL:

15 Fisiese Wetenskappe/V1 DoE/Additional Exemplar 008 NSS NATIONAL SENIOR CERTIFICATE NASIONALE SENIOR SERTIFIKAAT DATA FOR PHYSICAL SCIENCES GRADE 1 PAPER 1 (PHYSICS) GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 1 VRAESTEL 1 (FISIKA) TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES NAME/NAAM SYMBOL/SIMBOOL VALUE/WAARDE Acceleration due to gravity Swaartekragversnelling Speed of light in a vacuum Spoed van lig in 'n vakuum Planck's constant Planck se konstante Gravitational constant Swaartekragkonstante Coulomb's constant Coulomb se konstante Charge on electron Lading op elektron Electron mass Elektronmassa Permittivity of free space Permittiwiteit van vry ruimte Permeability of free space Permeabiliteit van vry ruimte g 9,8 m s - c 3,0 x 10 8 m s -1 h 6,63 x J s G 6,67 x N m kg k 9,0 x N m C e m e -1,6 x C 9,11 x kg ε 0 8,85 x 10-1 F m -1 µ 0 4 π x 10-7 T m A -1

16 Physical Sciences/P1 DoE/Additional Exemplar 008 TABLE : FORMULAE/TABEL : FORMULES MOTION/BEWEGING v f = v i + a t vf = vi + a x or/of v f = v i + a y FORCE/KRAG x = v t + a t or/of f i x = t F net = ma p = mv F net t = p = mv mv F g = mg f i i 1 v + v or/of WORK, ENERGY AND POWER/ARBEID, ENERGIE EN DRYWING W = F x cos θ U = E P = mgh 1 K Ek = mv W = K = Ek W P = P = Fv t = E E = kf ki WAVES, SOUND AND LIGHT/GOLWE, KLANK EN LIG 1 y = v i t + a t v f + v i y = t v = f λ or/of v = νλ f v ± v f 1 T = or/of f L L = s hf v ± v s h mλ λ = sin θ = mv a 1 1 hf = W0 + mv = hf0 + mv T = 1 ν E= or/of E =hν or/of E = h c λ MATTER AND MATERIALS/MATERIE EN MATERIALE F = k x Stress/Spanning Strain/Vervorming x = l = F A

17 Physical Sciences/P1 DoE/Additional Exemplar 008 ELECTRICITY AND MAGNETISM/ELEKTRISITEIT EN MAGNETISME Imax I I rms = / I wgk = Vmax Vrms = / V Φ = BA wgk = maks V maks Φ ε = N t P average = V rms I rms / P gemiddeld = V wgk I wgk V V wgk rms P average = / P gemiddeld = R R P average = I rmsr / P gemiddeld = I wgkr ELECTROSTATICS/ELEKTROSTATIKA kq1q kq F= E = r r V kq1q E = = d r F E = Q = It q Q ε C = C = 0 A V d U ELECTRIC CIRCUITS/ELEKTRIESE STROOMBANE R = V = I R R R. p 1 Rs 1 + = R + R... emf/emk(ε ) = I(R + r)

18 Physical Sciences/P1 DoE/Additional Exemplar 008 EXAMINATION NUMBER ANSWER SHEET/ANTWOORDBLAD QUESTION 1/VRAAG (1) 1. (1) 1.3 (1) 1.4 (1) 1.5 (1) [5] QUESTION /VRAAG.1 (1). (1).3 (1).4 (1).5 (1) [5] QUESTION 3/QUESTION () () () () () [10] QUESTION 4/VRAAG A B C D 4. A B C D 4.3 A B C D 4.4 A B C D 4.5 A B C D (5 x 3) [15] TOTAL SECTION A/TOTAAL AFDELING A: 35

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