Physical Sciences Grade 12 Mpumalanga November 2014 QP (Eng)

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE EXAM PHYSICAL SCIENCES: PHYSICS (P1) GRADE 12 SEPTEMBER 2014 MARKS: 150 TIME: 3 HOURS This paper consists of 16 pages and 2 data sheets Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 2 DBE/September 2014 CAPS INSTRUCTIONS AND INFORMATION 1. Write your name on the ANSWER BOOK. 2. Answer ALL the questions in the ANSWER BOOK. 3. This question paper consists of TWO sections: SECTION A: (20) SECTION B: (130) 4. You may use a non-programmable calculator. 5. You may use appropriate mathematical instruments. 6. Number the answers correctly according to the numbering system used in this question paper. 7. YOU ARE ADVISED TO USE THE ATTACHED DATA SHEETS. 8. Give brief motivations, discussions et cetera where required. 9. Round off your final numerical answers to a minimum of TWO decimal places. Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 3 DBE/September 2014 CAPS SECTION A 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 (1.1-1.10) in the ANSWER BOOK. 1.1 A ball, mass m, moves towards a wall, collides inelastically with the wall and moves back. vi vf Which one of the following vector diagrams shows the correct relationship between the initial momentum (pi) of the ball, the final momentum (pf) of the ball and the change in momentum (∆p) the ball experiences? pi pi A pf pf B ∆p ∆p pi pi C D pf pf ∆p ∆p (2) 1.2 Two asteroids, 1 000 km apart, experience an attractive gravitational force F between each other. If the asteroids move away from each other until a distance of 2 000 km separates them, the magnitude of the new gravitational force will be… 1 A  4 1 B  2 C √2 D 4 (2) 1.3 A ball is thrown vertically downwards from a certain height above the floor. The Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 4 DBE/September 2014 CAPS ball bounces a few times from the floor. The velocity–time graph below represents the motion of the bouncing ball from the moment it was thrown. Ignore the effects of friction. Velocity (m·s-1) R ● ●P Time (s) ●S Which point (P, Q, R or S) on the graph represents the coordinates of the maximum height after the first bounce? A P B Q C R D S (2) 1.4 A constant force F applied to an object causes a change in position, ∆x. The graph of force versus position for the object is given below. Assume that the force F and the change in position are in the same direction. Force (N) F x Position (m) Which ONE of the following statements is correct? A The gradient of the graph represents the net work done by the force. B The gradient of the graph represents the change in kinetic energy. C The area under the graph represents the work done by the force. D The area under the graph represents the power dissapated by the force. (2) 1.5 The reason why the observed pitch of an ambulance decreases as the ambulance moves away from a stationary observer, is because the Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 5 DBE/September 2014 CAPS A amplitude of the sound wave decreases. B amplitude of the sound wave increases. C wavelength of the sound wave decreases. D wavelength of the sound wave increases. (2) 1.6 Two identical metal spheres X and Y, on isolated stands, have charges of +6 nC and -2 nC respectively. Y is brought into contact with X. Y is then placed in its original position again. +6 nC -2 nC X Y The final charge on each sphere is: X Y A 0 nC 0 nC B 3 nC -1 nC C 2 nC 2 nC D 4 nC 4 nC (2) 1.7 The internal resistance of the battery in the circuit diagram below is negligible. Copyright reserved AA Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 6 DBE/September 2014 CAPS V • • Switch S is closed. Which ONE of the following represents the change in the voltmeter and ammeter readings? Voltmeter reading Ammeter reading A Increases Increases B Increases Decreases C Decreases Decreases D Decreases Increases (2) 1.8 In the circuit diagram below, the power dissipated by the 3 Ω resistor is P. The power dissipated by the 6 Ω resistor is… 3Ω 6Ω A 1  4 B 1  2 C 2 D 4 (2) 1.9 An electric iron is rated 1 400 W ; 220 V. It takes 3 hours to iron a load of clothes. The cost to iron these clothes, if the cost of electricity is R1,30 per kWh, is… A R 1,82 Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 7 DBE/September 2014 CAPS B R 5,46 C R 8,58 D R 18,20 (2) 1.10 Blue light of different intensities is shone onto the cathode of a photo-electric cell. Photo-electrons are emitted from the cathode. Which ONE of the following graphs represents the correct relationship between the maximum kinetic energy of the emitted photo electrons and the intensity of the incident light? Ek Ek Intensity Intensity A B Ek Ek Intensity Intensity C D (2) TOTAL SECTION A: [20] SECTION B INSTRUCTIONS 1. Start each question on a new page. Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 8 DBE/September 2014 CAPS 2. Leave one line open between two sub-questions, for example between QUESTION 2.1 and 2.2. 3. Show the formulae and substitutions in ALL calculations. 4. Round off your final numerical answers to a minimum of two decimal places. QUESTION 2 (Start on a new page.) A light inelastic string connects two blocks of mass 1,5 kg and 2 kg respectively. A force is applied at an angle of 20° on block A. F B A 20° 1,5 kg 2 kg If a force F of 8,25 N is applied on block A, the blocks move at a CONSTANT VELOCITY on the rough surface. 2.1 Calculate the horizontal component of the applied force F. (2) 2.2 Calculate the magnitude of the normal force acting on block A. (3) 2.3 Calculate the coefficient of kinetic friction between the blocks and the rough (4) surface. 2.4 How will the frictional force on block A change if the angle of the force changes to 15°? Write down INCREASES, DECREASES or REMAINS THE SAME. (1) [10] QUESTION 3 (Start on a new page.) A boy kicks a ball vertically upwards from a height of 0,6 m above the ground. The ball moves past the top of a building, 21 m higher than the point from where he kicked the ball. The ball hits the roof of the building 3,1 s after it was kicked. The ball bounces once off the roof of the building and then comes to rest. Ignore all effects of air resistance. Copyright reserved X Please turn over •

Downloaded from hlayiso.com Physical Sciences/P1 9 DBE/September 2014 CAPS 21 m 0,6 m 3.1 Write down the magnitude and direction of the acceleration of the ball at point X. (2) 3.2 Calculate the magnitude of the velocity with which the ball was kicked. (4) 3.3 Calculate the maximum height that the ball reaches above the ground. (4) 3.4 Refer to the sketch and state whether the collision of the ball on the roof is ELASTIC or INELASTIC. Give a reason for the answer. (2) 3.5 Sketch a postion versus time graph for the complete motion of the ball, from the moment it was kicked until it comes to rest. Use the roof of the building as the zero of position. Indicate the following on the graph: • The position of the ball when the boy kicks it. • The position at point X. • The time when the ball hits the roof the first time. (5) [17] QUESTON 4 (Start on a new page) A boy on roller blades with his hands on a fully loaded trolley, mass 18 kg, moves west at 5 m·s-1 over a frictionless surface as shown in the sketch. The boy now pushes the trolley so that he moves at 1 m·s-1 east after this push. The mass of the boy and his roller blades is 45 kg. N Copyright reserved W Please turn over E S

Downloaded from hlayiso.com Physical Sciences/P1 10 DBE/September 2014 CAPS 5 m·s-1 18 kg 4.1 State the conservation principle that is applicable during the interaction between the boy and the trolley. (2) 4.2 Calculate the velocity of the trolley directly after the boy pushed it. (4) 4.3 During the pushing motion of the boy on the trolley, the trolley experiences an impulse. How does the magnitude of the impulse that the boy experiences compare to that of the trolley? Write down INCREASES, DECREASES or REMAINS THE SAME and explain your answer. (3) 4.4 If the force exerted on the trolley lasts 0,4 s, calculate the force that the boy exerts on the trolley. (4) [13] QUESTION 5 (Start on a new page) A constant force F is applied to a crate of mass 25 kg to move it upwards along a frictionless inclined plane. When it reaches point A, its speed is 12 m·s-1 and 10,8 m·s-1 when it reaches point B which is 3,5 m further up the incline. 3,5 m Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 11 DBE/September 2014 CAPS B -1 12 m·s F A 30° 5.1 Draw a free force diagram showing ALL the forces acting on the crate while it is moving up the incline. (3) 5.2 Is mechanical energy conserved during this motion? Write down YES or NO and briefly explain the answer. (2) 5.3 Write down the NAME of the conservative force that acts on the crate. (1) 5.4 Give a reason why the normal force does no work on the crate during its motion up the incline. (1) 5.5 In which direction does the net force act on the crate as it moves up the incline? Write only FROM A TO B or FROM B TO A. (1) 5.6 Use ENERGY PRINCIPLES to calculate the magnitude of the force F. (6) [14] QUESTION 6 (Start on a new page) A whale swims directly towards a stationary submarine at 8 m·s-1. The sonar system of the submarine has a frequency of 23 000 Hz. Take the speed of the sonar wave in sea water as 1 435 m·s-1. 8 m·s-1 Whale Submarine 6.1 Define the Doppler effect. (2) 6.2 How does the frequency that the whale observes compare to the frequency sent out by the submarine? Write down only HIGHER, LOWER or STAYS THE SAME. (1) 6.3 Calculate the frequency of the sound wave heard by the whale. (4) The Doppler-effect is also used to monitor the movement of remote stars. During such a study of a star it was observed that the absorption line of red light moved to 688 nm. On the earth the absorption line of red light is observed at 653 nm. 6.4 Is the remote star moving NEARER TO or FURTHER AWAY from the earth? Give a reason for your answer. (4) [16] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 12 DBE/September 2014 CAPS QUESTION 7 (Start on a new page.) In the diagram below, a point charge, Q2, with a charge of -4 nC is placed 6 mm east of an identical point charge Q1. Point X is a distance d east of Q2. N 6 mm d W E ● ● ● Q1 Q2 X S -4 nC -4 nC 7.1 Draw the net electric field pattern due to charges Q1 and Q2. (3) 7.2 The electric field at point X, due to ONLY Q1, is 4,44 x 105 N·C-1 west. Calculate the distance d. (5) A charge Q3 of -5 nC is now placed 10 mm due north of charge Q1. -5 nC ● Q3 10 mm Q1 Q2 ● ● 6 mm 7.3 Write down Coulomb’s law in words. (2) 7.4 Calculate the magnitude of the net force that the charge Q1 will experience due to the charges Q2 and Q3. (6) [16] QUESTION 8 (Start on a new page.) Learners investigate the conductivity of two metal wires P and Q that are made of different materials. They connect one wire at a time in a circuit diagram as shown below. • • A Wire Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 13 DBE/September 2014 CAPS V The potential difference across each wire is increased by a constant amount and the current is measured accordingly. The learners represent their observations in the following sketch graph. Wire P Current (A) Wire Q Potential difference (V) 8.1 Write down the investigative question. (2) 8.2 State TWO variables that the learners had to keep constant in the investigation. (2) 8.3 With reference to the gradients of the graph, determine which one of the wires is the better conductor. Write down P or Q and explain your answer. (3) [7] QUESTION 9 (Start on a new page.) In the circuit diagram below the light bulb L has a resistance of 40 Ω and the battery has an internal resistance of 3 Ω. The reading on the voltmeter decreases with 4,5 V when the switch S is closed. 3Ω Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 14 DBE/September 2014 CAPS • V 30 Ω 20 Ω S • A L 40 Ω 9.1 Explain why there is a decrease in the voltmeter reading when the switch S is closed. (2) 9.2 The switch S is closed. Calculate the: 9.2.1 current in the battery. (3) 9.2.2 emf of the battery. (5) 9.2.3 reading on the ammeter. (3) 9.3 The 20 Ω resistor suddenly burns out. How will the power dissipated in the light bulb change? Write down INCREASES, DECREASES or REMAINS THE SAME and explain the answer fully. (4) [17] QUESTION 10 (Start on a new page.) The following simplified sketches represent an alternating current (AC) generator that is rotated clockwise. Sketch A Sketch B N S N S Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 15 DBE/September 2014 CAPS X Y 10.1 Write down the energy conversion that takes place in an AC generator. (1) 10.2 Write down the name of the component 10.2.1 labelled X (1) 10.2.2 labelled Y (1) 10.3 The maximum current output of this AC generator is 21 A. A graph of the potential difference output of the generator against time is shown below. 400 Potential difference (V) 300 200 100 0 t1 -100 Time (s) -200 (s) -300 -400 10.3.1 Which ONE of the sketches (A or B) shows the position of the coil at the time t1 on the graph? (1) 10.3.2 Calculate the average power generated by the generator. (5) [9] QUESTION 11 (Start on a new page.) Light of different frequencies is irradiated onto the metal cathode R of a photo-cell. The kinetic energy of the released photo-electrons is measured and shown in the graph below. Ek (J) R • Copyright reserved P Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 16 DBE/September 2014 CAPS 5,79 Frequency ( ×1014 Hz) 11.1 Explain why no photo-electrons are released when light of frequency P is used. (2) 11.2 The photo-cell is now replaced with one which contains a metal cathode S and is irradiated with light of different frequencies. The metal cathode S has a higher work function than metal cathode R. Redraw the above graph in your answer book. Indicate the relationship between the frequency and the kinetic energy of metal cathode S on the same axis. Label the graphs very clearly as R and S. (2) Ultraviolet light with a frequency of 1,5 × 1015 Hz is irradiated on the surface of metal cathode R. Photo-electrons are released. 11.3 Calculate the energy of a photon of ultraviolet light. (3) 11.4 Calculate the maximum kinetic energy of the photo-electrons. (4) [11] QUESTION 12 (Start on a new page.) The following table represents the different energy levels of the hydrogen atom as well as the corresponding energy values, in joule (J) of each energy level. ENERGY LEVEL ENERGY VALUE n=4 E = -1,36 × 10-19 J n=3 é E = -2,40 × 10-19 J n=2 E = -5,44 × 10-19 J Copyright reserved Please turn over -18

Downloaded from hlayiso.com Physical Sciences/P1 17 DBE/September 2014 CAPS 12.1 The colour of light and its corresponding wavelength is given in the table below. COLOUR WAVE LENGTH (×10-9 m) Red 650 Orange 590 Yellow 570 Green 510 Blue 475 Violet 400 Determine the colour of light emitted when an electron falls back from the third to the second energy level. Show ALL calculations. (6) [6] TOTAL SECTION B: [130] GRAND TOTAL: 150 DATA FOR PHYSICAL SCIENCES GRADE 12 PAPER 1 (PHYSICS) TABLE 1: PHYSICAL CONSTANTS NAME SYMBOL VALUE Acceleration due to gravity g 9,8 m·s-2 Universal gravitational constant G 6,67 × 10-11 N·m2·kg-2 Radius of Earth RE 6,38 × 106 m Mass of Earth ME 5,98 × 1024 kg Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 18 DBE/September 2014 CAPS Speed of light in a vacuum c 3,0 x 108 m·s-1 Planck's constant h 6,63 x 10-34 J·s Coulomb's constant k 9,0 x 109 N·m2·C-2 Charge on electron e -1,6 x 10-19 C Electron mass me 9,11 x 10-31 kg TABLE 2: FORMULAE MOTION v f = v i + a ∆t ∆x = v i ∆t + 21 a∆t 2 OR ∆y = v i ∆t + 21 a∆t 2  v +vf   v + vf  2 2 2 v f = v i + 2a∆x OR v f = v i + 2a∆y 2 ∆x =  i  ∆t OR ∆y =  i  ∆t  2   2  FORCE Fnet = ma p = mv Fnet ∆t = ∆p ∆p = mv f − mv i w = mg Gm1 m2 Gm F= g= r2 r2 fs(max) = µsN fk = µkN WORK, ENERGY AND POWER W = F∆x cos θ U = mgh OR EP = mgh 1 1 Wnet = ∆K OR W net = ∆Ek K = mv 2 OR Ek = mv 2 2 2 ∆K = Kf – Ki OR ∆Ek = Ekf - Eki W Wnc = ∆K + ∆U OR W nc = ∆Ek + ∆Ep P= ∆t Pavg = F·vavg WAVES, SOUND AND LIGHT 1 v=fλ T= f v ± vL c fL = fs E = hf OR E= h v ± vs λ E = W o + Kmax OR E = W o + Ek(max) with 1 1 E = hf en W o = hfo en Kmax = 2 mv2max OR Ek(max) = 2 mv2max ELECTROSTATICS Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P1 19 DBE/September 2014 CAPS kQ1Q 2 kQ F= E= r 2 r2 F W E= V= q q Q Q n = e OF n = q e ELECTRIC CIRCUITS V R= emf (E) = I(R + r) I Rs = R1 + R2 + ... 1 1 1 q=I ∆t = + + ... R p R1 R 2 W = Vq W P= W = VI ∆ t ∆t P = VI W = I2R ∆ t 2 P = I 2R V ∆t W= V2 R P= R ALTERNATING CURRENT Paverage = Vrms I rms I I rms = max 2 Paverage = I 2rmsR Vmax Vrms = 2 Vrms 2 Paverage = R Copyright reserved Please turn over