GAUTENG DEPARTMENT OF EDUCATION PREPARATORY EXAMINATION

Transcription

1 GAUTENG DEPARTMENT OF EDUCATION PREPARATORY EXAMINATION PHYSICAL SCIENCES FIRST PAPER MARKS: 150 Pages 3 TIME: 3 hours 3

2 (First Paper) 10841/14 GAUTENG DEPARTMENT OF EDUCATION PREPARATORY EXAMINATION PHYSICAL SCIENCES (First Paper) TIME: 3 hours MARKS: 150 INSTRUCTIONS AND INFORMATION 1. Write your name in the appropriate space on the ANSWER BOOK.. This question paper consists of TWELVE questions. Answer ALL the questions in the ANSWER BOOK. 3. Start EACH question on a NEW page in the ANSWER BOOK. 4. Number the answers correctly according to the numbering system used in this question paper. 5. Leave ONE line between two subquestions, for example between QUESTION.1 and QUESTION.. 6. You may use a non-programmable calculator. 7. You may use appropriate mathematical instruments. 8. You are advised to use the attached DATA SHEETS. 9. Show ALL formulae and substitutions in ALL calculations. 10. Round off your final numerical answers to a minimum of TWO decimal places. 11. Give brief motivations, discussions, et cetera where required. 1. Write neatly and legibly.

3 (First Paper) 10841/14 3 QUESTION 1: MULTIPLE-CHOICE QUESTIONS Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. Write only the letter (A D) next to the question number (.1.10) in the ANSWER BOOK. 1.1 The following diagram shows a racing car R driving along a straight line to the right. oil spill R P The driver of the racing car applies the brakes when the car reaches the oil spill at position P. In which of the following directions will the racing car R slide? A B C D ()

4 (First Paper) 10841/ Diagram A shows a 1 kg mass suspended by a Newton scale attached to the ceiling. In diagram B, the same 1 kg mass is now suspended from a weightless, frictionless pulley by tying the rope to the floor. If the reading on the scale in diagram A is 9,8 N, what will the scale read in diagram B? A B C D 4,9 N 9,8 N 14,7 N 19,6 N ()

5 (First Paper) 10841/ The gravitational force between two objects is F when their centres are a distance d apart. What would the magnitude of the force be in terms of F if the mass of one object is doubled and the distance d halved? A B C D 8F F F F () 1.4 An object has a momentum p for a time of t seconds. Which ONE of the following graphs correctly shows the acceleration-time relationship for this time interval? A. B. C. D. a a a a o o o o t t t t 1.5 Which ONE of the following statements regarding the redshift of light as a result of the Doppler effect is true? A B C D If a source of blue light is moving away from the observer, the light will appear violet If a source of red light is moving away from the observer, the light will appear blue If a source of blue light is moving away from the observer, the light will appear more green If a source of red light is moving away from the observer, the light will appear more orange ()

6 (First Paper) 10841/ Which ONE of the following combinations is correct regarding the properties of electric field lines? Direction Strength of field A Positive to negative Strongest where the lines are the most dense B Negative to positive Weakest where the lines are the least dense C North to south Strongest where the lines are the most dense D North to south Weakest where the lines are the least dense () 1.7 Two charged spheres, A and B, are placed on insulated stands a distance r apart, as shown below. The magnitude of the electrostatic force between them is F. r A -4q q B The spheres are allowed to touch each other and are then moved back to their original positions. The magnitude of the electrostatic force in terms of F will now be A B C D 8 F F F F ()

7 (First Paper) 10841/ The circuit diagram shows two light bulbs of resistance 4 Ω and Ω each connected in parallel to the circuit. The two resistors of resistance 4 Ω and 6 Ω each are connected in series to the circuit. If the Ω light bulb burns out what happens to the reading on V P? A B C D Stays the same Decreases Increases Becomes zero () 1.9 The magnet in the following diagram is moving away from the solenoid. The induced current flows through the resistor in a direction from A B C D Q to R R to Q Q to R and then from R to Q R to Q and then from Q to R ()

8 (First Paper) 10841/ An excited electron is in energy level 3. The maximum possible emission spectrum lines that this electron can generate is A B C D () [0]

9 (First Paper) 10841/14 9 QUESTION (Start on a new page.) An 8 kg wooden block is attached to a kg wooden block by means of a weightless inelastic string which passes over a frictionless pulley. The block accelerates down a rough plane inclined at 0 to the horizontal as shown below. a 8 kg kg 0 The tension in the string is 1 N..1 Define acceleration. (). Draw a labelled force diagram of all the forces acting on the 8 kg block. (3).3 Prove using a calculation that the magnitude of the acceleration of the system is 0,7 m s -. (3).4 Calculate the magnitude of the frictional force experienced by the 8 kg block. (4) [1]

10 Position (m) PHYSICAL SCIENCES (First Paper) 10841/14 10 QUESTION 3 (Start on a new page.) The position-time graph for a tennis ball thrown vertically upwards from the second floor of a school building is shown below. Ignore all effects of air friction. 6,5 0 t 1 t Time (s) The height of the second floor is 6,5 m. The ball rises 0,9 m from the point of projection before it starts to fall to the ground. 3.1 Write down the magnitude and direction of the acceleration of the ball while it is moving upwards. () 3. Calculate the time t 1 it takes the ball to reach its maximum height. (4) 3.3 Calculate the initial velocity of the tennis ball the instant it is released. (4) 3.4 Sketch a velocity-time graph for the motion of the ball from the moment it is thrown vertically upwards till it reaches the ground. Label the axes and show all the relevant values on the graph. (4) [14]

11 ½(1 496) km PHYSICAL SCIENCES (First Paper) 10841/14 11 QUESTION 4 (Start on a new page.) The diagram below shows a planet Z and its two moons X and Y at right angles to each other. The average distance between the centre of the planet and moon X is km and the average distance between the centre of the planet and moon Y is ½(1 496) km. Z km M X = 1, kg M Y = (1, ) kg Take the mass of X as 1, kg, the mass of the planet Z as 5, kg and the mass of Y as twice the mass of X. 4.1 Calculate the gravitational force between moon X and planet Z. (4) 4. Write down the magnitude of the gravitational force that moon Y exerts on the planet Z. () 4.3 Calculate the magnitude of the net gravitational force of the two moons on the planet. () [8]

12 (First Paper) 10841/14 1 QUESTION 5 (Start on a new page.) Two identical objects P and Q with a mass of 1 kg each, are moving side by side with an initial velocity of 5,5 m s -1 east on a horizontal surface. The following graphs show the net force experienced by each object respectively during the same time interval. Fnet (N) Object P Fnet (N) Object Q t (s) t (s) Calculate the total impulse experienced by object Q in 10 s. (3) 5. Compare without using any calculations the total impulse for object P with that of object Q. Write down only GREATER THAN, LESS THAN or EQUAL TO. (1) 5.3 Calculate the final velocity of object Q. (4) [8]

13 (First Paper) 10841/14 13 QUESTION 6 (Start on a new page.) A cyclist pushes his bicycle of mass 6,1 kg up an incline with a force of 0 N. The bicycle is pushed from an initial velocity of 5 m s -1 from point A to point B. The road is inclined at 10 to the horizontal and the distance from A to B is 3 m as shown below. 3 m 0 N B A 10 The road surface exerts a force of friction of 11 N on the bicycle tyres. 6.1 Calculate the work done by the cyclist on the bicycle. (3) 6. Use the work-energy theorem and calculate the magnitude of the velocity of the bicycle at 3 m. (5) 6.3 Explain why frictional forces are regarded as non-conservative forces. () [10]

14 (First Paper) 10841/14 14 QUESTION 7 (Start on a new page.) 7.1 Keenan standing at the top of the Leaning Tower of Pisa accidentally drops his cell phone when it starts ringing at a frequency of 497 x 10 3 Hz. The height of the tower is 56 m Calculate the speed of the cell phone at a height of 18 m by using the law of conservation of mechanical energy. (4) Nerisse standing at the bottom of the tower hears the phone ringing as it falls towards her. Ignore the effects of air friction Calculate the frequency of the sound observed by Nerisse when the phone is at the height of 18 m above ground. Take the speed of sound in air as 340 m s -1 (4) Explain in terms of wavelength and frequency of sound why Keenan who is at the top of the tower, observes a lower frequency of sound than the value calculated in QUESTION (3) How will the frequency of sound observed by Nerisse compare at a height of 18 m to that at 3 m? Write only HIGHER, LOWER or STAYS THE SAME. (1) 7. Speed cameras determine the speed of a car by measuring the signal of a radio wave reflected by the car Explain why the speed camera cannot measure the speed of the car accurately at the moment the car passes the camera. (1) 7.. What is the speed of the radio wave in air? Give a reason for your answer. () [15]

15 (First Paper) 10841/14 15 QUESTION 8 (Start on a new page.) The diagram below shows two spheres, A of charge 4, C and B of charge + 9, C on insulated stands. The distance between the centres of the two spheres is 0,35 m. 4, C A 0,35 m + 9, C B 8.1 Draw the field pattern diagram for the net electric field present between the two charges. (3) 8. Calculate the magnitude and direction of the electrostatic force exerted by sphere B on sphere A. (4) 8.3 Calculate the strength of the electric field at B as a result of charge A. (4) [11]

16 (First Paper) 10841/14 16 QUESTION 9 (Start on a new page.) Sandile and Peter built a battery for the science fair. They used potatoes for the cells with zinc and copper plates as electrodes. Sandile and Peter were curious to find out how many potato cells connected in series would be needed to make a penlight bulb glow. 9.1 Write a suitable hypothesis for the investigation. () 9. Write down the dependent variable for the investigation. (1) Sandile and Peter started with two potatoes connected in series as shown in the picture above. They used a voltmeter directly over the outer electrodes and measured a potential difference of 1,6 V. Next they connected a 1,5 V penlight bulb between the electrodes. The learners found that the bulb did not glow. When they measured the potential difference across the globe it was 0,0V. 9.3 What is the emf of the battery with two potato cells connected in series? (1) 9.4 Give a reason why the potential difference across the bulb was only 0,0V. (1) 9.5 The bulb has a resistance of Ω. Calculate the power dissipated by the bulb even though it is not visibly glowing. (3) [8]

17 (First Paper) 10841/14 17 QUESTION 10 (Start on a new page.) The circuit diagram below shows two resistors of resistance 4 Ω and 5 Ω each connected in parallel to resistor R 1 of unknown resistance. The battery has an emf of 15 V and an unknown internal resistance. V 1,9 V S emf = 15 V; r 4 Ω 5 Ω R 1 A 1,5 A 10.1 State Ohm s law in words. () When switch S is closed, the ammeter has a reading of 1,5 A and the voltmeter has a reading of 1,9 V. 10. Calculate the resistance of resistor R 1. (3) 10.3 Calculate the equivalent resistance of the parallel circuit. (3) 10.4 Calculate the internal resistance of the battery. (4) [1]

18 (First Paper) 10841/14 18 QUESTION 11 (Start on a new page.) 11.1 Study the diagram of an electric motor given below. The coil rotates between the opposite poles X and Y of two magnets Is this a DC or an AC motor? Give a reason for your answer. () State TWO changes that can be made to this motor to increase the rate of rotation. () What is the polarity of the two magnetic poles X and Y? () 11. Generators need a source of mechanical energy to turn the coil inside a magnetic field. The picture below shows an example of a wind generator. A wind generator has rotor blades that are 100 m in diameter. When the wind blows at maximum speed, the generator produces a maximum AC-current of 80 A in a resistor of 510 Ω Calculate the rms potential difference across the resistor. (5) 11.. Calculate the average power produced by the generator. (3) Draw a sketch graph of the change in current generated by this AC-generator. Show TWO full cycles for the change in current on the graph. Indicate the appropriate values of the current on the axis. (4) [18]

19 (First Paper) 10841/14 19 QUESTION 1 (Start on a new page.) 1.1 The graph below shows the relation between the maximum kinetic energy for electrons emitted from the surface of a certain metal when it is illuminated with electromagnetic radiation of different frequencies Define the work function for a specific metal. () 1.1. Give the magnitude of the threshold frequency of the metal as shown on the graph. () Calculate the maximum velocity of an emitted electron if electromagnetic radiation with a frequency of Hz is shone onto the metal surface. (5) The graph is described as the best fit line. Explain what this means. (1)

20 (First Paper) 10841/ The following diagram shows different lines of the line emission spectra (coloured lines on a black background) and the absorption spectrum (black lines on a coloured background) of the hydrogen atom respectively. The lines correspond to the transition of electrons between specific energy levels. Hydrogen Absorption Spectrum Hydrogen Emission Spectrum 400nm 700nm H Alpha Line 656nm Transition N=3 to N= 1..1 Explain the difference between an emission spectrum and an absorption spectrum. () 1.. What is the most likely colour for the H-Alpha line? Choose from RED, GREEN or VIOLET. Give a reason for your answer. () [14] GRAND TOTAL: 150

21 (First Paper) 10841/14 1 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 Universal gravitational constant Universele gravitasiekonstant Speed of light in a vacuum Spoed van lig in 'n vakuum Planck's constant Planck se konstante Coulomb's constant Coulomb se konstante Charge on electron Lading op elektron Electron mass Elektronmassa Mass of earth Massa van die aarde Radius of earth Radius van die aarde g 9,8 m s - G 6,67 x N m kg c 3,0 x 10 8 m s -1 h 6,63 x J s k 9,0 x N m C e m e M E R E -1,6 x C 9,11 x kg 5,98 x 10 4 kg 6,38 x 10 3 km

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23 (First Paper) 10841/14 TABLE : FORMULAE/TABEL : FORMULES MOTION/BEWEGING vf v f 1 1 vi a t Δx viδt a t or/of Δy viδt a t v i v f v i v f vi a x or/of v f vi a y Δx Δt or/of Δy Δt FORCE/KRAG F net ma f s max = µ s N p mv f k = µ k N F net t p p mv 1 F f mv i w mg Gm m M d g = G d WORK, ENERGY AND POWER/ARBEID, ENERGIE EN DRYWING W F x cos U mgh or/of E P mgh 1 K mv or/of W nc 1 Ek mv K U or/of Wnc Ek Ep Pave Fv ave W net K or/of Wnet Ek K K f K i or/of Ek Ekf Eki W P t WAVES, SOUND AND LIGHT/GOLWE, KLANK EN LIG v f f v v L L L fs / L b v v s v vb E W o E k max where/waar E hf and/en W0 hf0 and/en E f 1 T f v v f E hf or/of k max 1 mv max or/ of E h c 1 K max mv max b.o.

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25 (First Paper) 10841/14 3 ELECTROSTATICS/ELEKTROSTATIKA kq Q 1 F E r Q n = q e W V q kq r F E q ELECTRIC CIRCUITS/ELEKTRIESE STROOMBANE V R I Rs R1 R R R R p 1 W = Vq W = VI t W= I R t W= V Δt R emf ( ε ) = I(R + r) emk ( ε ) = I(R + r) q I t W P Δt P = VI P = I R V P R ALTERNATING CURRENT/WISSELSTROOM Imax Irms / I I wgk maks V V max rms / V V wgk maks P P I / Pgemiddeld V wgk Iwgk average V rms average I rms rms R / P R gemiddeld I wgk Vrms P average R / V P gemiddeld R wgk END