GR11 Physics exemplar examination

Study & Master Support Pack | Grade 11 Physical Sciences Physics exemplar examination This pack of Exemplar exam papers for the study of the Physical Sciences Grade 11 CAPS curriculum will support your learners on the road to success. Learners can work through these individually at home or these could form the basis of a catch-up class or online lesson. You have permission to print or photocopy this document or distribute it electronically via email or WhatsApp. Cambridge University Press Africa is a proudly South African publisher. For more information on our Study & Master CAPS-approved textbooks and valuable resource materials, visit www.cambridge.org Brighter thinking I Better learning 58 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1 www.cambridge.org

Physics exemplar examination: Paper 1 Section A Question 1 Various 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 Which triangle can be used to determine the magnitude of the resultant of the four forces shown below? 5N 6N 11 N 15 N 17 5 20 15 10 5 11 6 A B C D (2) 1.2 In the diagram below the forces P, Q and 100 N are in equilibrium. The 100 N force acts vertically downwards. P Q y x 100 N The resultant of P and Q: A cannot be calculated unless either P or Q is given B cannot be calculated unless angles x and y are given C is 100 N vertically downwards D is 100 N vertically upwards. (2) E X E M P L A R E X A M PA P E R S 59

1.3 John suspends a bag of apples from a spring balance held vertically. The balance itself weighs 10 N and John notes that the balance reads 40 N. He then lets go of the balance and the balance and apples fall freely. What would the reading be on the balance while falling? A 50 N B 40 N C 30 N D 0N (2) 1.4 What is the relationship between the mass of a body and its acceleration? (Ignore air friction.) A Acceleration is independent of mass. B Acceleration is proportional to the body’s mass. C Acceleration is inversely proportional to the body’s mass. D Acceleration is proportional to the square of the mass. (2) 1.5 Two asteroids, 1 000 km apart, attract each other with a gravitational force of F. If the two asteroids move away from each other to a distance of 3 000 km, how great will the gravitational force be? 1 A 9F B 9F 1 C 3F D 3F(2) 1.6 Which of the following ray diagrams is correct? A B C D water water water water air air air air (2) 1.7 Diffraction of light is proof of the: A particle nature of light B wave nature of light C dual nature of light D dispersive nature of light. (2) 1.8 The force between two identical positive point charges of 3 µC each, 1 m apart, is: A 8,1 3 10−8 N attractive B 8,1 3 10−8 N repulsive C 8,1 3 10−2 N repulsive D 8,1 3 10−2 N attractive. (2) 60 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

1.9 Charge flows through the wire in the direction shown in the diagram. I This causes a magnetic field that, in the centre of the coil, points from: A left to right B right to left C top to bottom D bottom to top. (2) 1.10 Three identical resistors can be connected in different ways, as illustrated in the circuits below. Which circuit diagram will allow the smallest current through the ammeter? 3V 3V A A A B 3V 3V A A C D (2) [20] E X E M P L A R E X A M PA P E R S 61

Section B Instructions and information 1. Start EACH question on a NEW page in the ANSWER BOOK. 2. Leave ONE line between each sub-question, for example between QUESTION 2.1 and QUESTION 2.2. 3. Show ALL formulae and substitutions in ALL calculations. 4. Round off your FINAL numerical answers to a minimum of TWO decimal places. 5. Give brief motivations, discussions, etc. where required. Question 2 y-axis 5 4 3 Vector A 2 1 1 2 3 4 5 x-axis –5 –4 –3 –2 –1 –1 –2 Vector B –3 –4 –5 2.1 Define the term ‘resultant of two forces’ in words. (2) 2.2 Use a calculation to determine each of the following: 2.2.1 the magnitude of Vector A in force units (2) 2.2.2 the direction of Vector B, measured clockwise from the positive y-axis. (3) 2.3 Use the tail-to-head method to calculate the magnitude and direction of the resultant (in force units) of vectors P and Q. Include a sketch diagram to show the vectors and resultant. (4) [11] Question 3 The course of an off-shore powerboat race is marked by three buoys A, B and C. Buoy B is 34 km from A along a bearing of 120°. Buoy C is 17 km from B along a bearing of 45°. Calculate the southerly component of a competitor’s displacement from A if he has completed the first two legs of the course from A to B to C. A 120° C 34 km 45° 17 km (5) B [5] 62 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 4 Rhinos are being moved from the Kruger National Park to Botswana. They are loaded into crates that are pulled up a ramp on frictionless rollers. The diagram shows a crate being held stationary on the ramp by means of a rope parallel to the ramp. The tension in the rope is 6 000 N. 000 N T56 15° 4.1 Explain how you can deduce that the forces acting on the crate are in equilibrium. (1) 4.2 Draw a labelled vector diagram of the forces acting on the crate and rhino. Regard the crate and rhino as one object. (3) 4.3 The crate has a mass of 650 kg. Determine the mass of the rhino. (5) 4.4 The crate is now pulled up the ramp at a constant speed. How does this action affect the forces acting on the crate and rhino? Justify your answer by mentioning any law or principle that applies to this situation. (3) [12] Question 5 Car A is towing car B with a light tow rope. The cars move along a straight, horizontal road. B A v 5.1 Write down Newton’s Second Law in words. (2) 5.2 As they start off, car A exerts a forward force of 600 N at its end of the tow rope. The force of friction on car B when it starts to move is 300 N. The mass of car B is 1 200 kg. Calculate: 5.2.1 the initial acceleration for car B (3) 5.2.2 the coefficient of kinetic friction of car B. (3) 5.3 After a while the cars travel at constant velocity. The force exerted on the tow rope is now 400 N. What is the magnitude and direction of friction on car B now? (2) 5.4 Towing with a rope is very dangerous. 5.4.1 Explain why towing with a rope is dangerous by using physics principles and laws. (2) 5.4.2 Explain what the advantage of a solid bar would be over a tow rope. (1) [13] E X E M P L A R E X A M PA P E R S 63

Question 6 Two mass pieces are suspended freely over a pulley. 2 kg 4 kg The weights of the mass pieces will accelerate the system. Calculate the acceleration of the system. (5) [5] Question 7 Two identical spheres with unequal masses m1 and m2, which are released simultaneously from rest, fall freely from a height h above the surface of the Earth. The two spheres reach the ground at the same time. 7.1 State Newton’s Law of Universal Gravitation in words. (3) 7.2 Use formulae to show that the gravitational acceleration of any object near the surface of the Earth, irrespective of its mass, can be given by: M g 5 G d 2 , where M 5 mass of the Earth; d 5 radius of the Earth. (2) 7.3 An object undergoing free fall on the planet Mars, experiences a gravitational acceleration of 3,8 m·s−2. The mass of Mars is 6,4 3 1023 kg. Calculate the radius of the planet Mars in metres. (4) 7.4 How will the mass and weight of the object on Mars compare to the mass and weight of the same object on Earth? (2) [11] Question 8 A diamond sparkles when light falls in on it. The refractive index of diamond is 2,42. 8.1 Define the term ‘refractive index’. (2) 8.2 The refractive index of glass is 1,52. How does the optical density of glass compare to that of diamond? (1) 8.3 Calculate the speed of light through diamond. (2) 8.4 A light ray travels from diamond to glass. The angle of incidence is 30°. 8.4.1 Draw a labelled diagram of the path of the light ray as it moves from diamond to glass. (4) 8.4.2 Calculate the angle of refraction by using Snell’s Law. (3) 8.5 Diamonds sparkle as a result of total internal reflection. 8.5.1 Calculate the critical angle of diamond. Take the refractive index of air as 1,00. (2) 8.5.2 Give two conditions for this phenomenon to take place in diamond. (2) [16] 64 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 9 Orange light with a wavelength of 590 nm passes through a slit 6 3 10−6 m wide and a diffraction pattern is observed on a screen as shown in the diagram. pattern screen B slit A 9.1 Define the term ‘diffraction’. (2) 9.2 Describe the diffraction pattern observed on the screen by labelling A and B. (2) 9.3 How does the brightness of the pattern on either side of A compare to that of A? Write down only brighter than, dimmer than or equal to. (1) 9.4 Which part of the pattern (A or B) is the result of destructive interference? (1) 9.5 How will the broadness of A differ if the following changes are made to the setup? Explain each answer. 9.5.1 Violet light with a wavelength of 400 nm is used. (2) 9.5.2 The slit width changes to 6 3 10−7 m. (2) 9.6 The phenomenon of diffraction can be explained by Huygens’ Principle. State this principle. (2) [12] Question 10 Two positive charges, A and B, of 50 nC each are positioned 9,50 cm from each other, as shown in the diagram. A is directly north from B. A 50 nC 6,72 cm 9,50 cm P 6,72 cm 50 nC B 10.1 Sketch the electric field pattern around the two charges. (3) E X E M P L A R E X A M PA P E R S 65

Point P is placed at equal distances from A and B. 10.2 Define the magnitude of the electric field at point P in words. (2) 10.3 Calculate the magnitude and direction of the resultant electric field at point P. (7) [12] Question 11 A solenoid with 2 100 turns has a cross-sectional area of 2,0 cm2. It is placed between the poles of a magnet so that the magnetic flux passes perpendicularly through the coil. The flux density changes from 0,50 T to 0,10 T in 0,12 s. 11.1 Name and state the rule that we use to determine the direction of the magnetic field associated with a solenoid. (3) 11.2 We use Faraday’s Law of electromagnetic induction to calculate the induced emf in a solenoid. 11.2.1 State Faraday’s Law of Electromagnetic Induction in words. (2) 11.2.2 Calculate the average emf that is induced across the ends of the solenoid. (5) [10] Question 12 Two learners set up an experiment to prove Ohm’s Law. In the first experiment they connected a resistor to a battery, ammeter and voltmeter. The readings on the ammeter and voltmeter were recorded in the table below. Number of cells Potential difference Current in resistor (A) across resistor (V) 1 1,5 0,06 2 3,0 0,12 3 4,5 0,18 In the second experiment they used the same circuit, but replaced the resistor with a light bulb. The readings were: Number of cells Potential difference Current in light bulb across resistor (V) (A) 1 1,5 0,21 2 3,0 0,30 3 4,5 0,35 12.1 Which quantity must remain constant during the experiment? (1) 12.2 State a hypothesis for the first experiment. (2) 12.3 Name the relationship between potential difference and current in experiment 1. (1) 12.4 Calculate the resistance of the resistor. (3) 12.5 Draw graphs of current versus potential difference for the resistor and light bulb on the same set of axes. Place current on the y-axis. (4) 66 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

12.6 Which of the two devices that were tested is an ohmic conductor? Justify your choice by referring to the graphs in Question 12.5. (1) 12.7 Which of the two devices has the highest resistance? (1) [13] Question 13 The diagram shows a combination of resistance wires used to heat the rear window of a motor car. Each wire has a resistance of 15 Ω. This combination is connected to the 12 V battery of a car. Ignore the internal resistance of the battery. 13.1 Calculate the effective resistance of the combination of wires in the window. (3) 13.2 Calculate the rate at which the wires will produce heat energy. (2) 13.3 If the wires were connected in series instead of parallel, explain whether you would expect a greater or lesser rate of heat production. (2) 13.4 A crack forms in the rear window of the car and breaks two of the resistance wires in the parallel combination, leaving only three working. By what factor does this change the rate at which heat energy is produced in the rear window? (3) [10] Total 150 marks E X E M P L A R E X A M PA P E R S 67

Physics exemplar examination: Paper 2 Section A Question 1 Various 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 Which ONE of the following bonds will be the most polar? A P–Cl B S–F C C−N D H−O (2) 1.2 The molecular shape of a molecule with the formula AB5 is: A bent B trigonal planar C tetrahedral D trigonal bipyramidal. (2) 1.3 The boiling point of CH4 is much lower than that of NH3. Which ONE of the following best explains this difference in boiling points? A NH3 molecules are more polar than CH4 molecules. B CH4 molecules are more polar than NH3 molecules. C There are hydrogen bonds between NH3 molecules. D There are induced dipole forces between CH4 molecules. (2) 1.4 Which of the following actions will NOT increase the temperature of an enclosed gas? A Increasing the volume while all other factors remain constant B Increasing the pressure while all other factors remain constant C Increasing the number of moles of the gas while all other factors remain constant D Increasing the average kinetic energy of the gas particles (2) 1.5 65,4 g hydrochloric acid react with 65,4 g zinc to form zinc chloride and hydrogen gas. The reaction equation is: 2HCl 1 Zn ZnCl2 1 H2 The limiting reagent is: A HCl B Zn C ZnCl2 D H2. (2) 68 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

1.6 1 litre of water contains … water molecules. A 1 mol B 6,02 3 1023 C 3,34 3 1025 D 2,69 3 1022 (2) 1.7 The graph represents the potential energy change for a certain reaction. Which combination is correct for this reaction? 600 Energy (kJ) 400 200 Course of reaction Type of reaction DH (kJ) A Endothermic 200 B Exothermic 400 C Endothermic 400 D Exothermic 200 (2) 1.8 Consider the incomplete chemical equation below. X 1 H2SO4 Mg(SO4)2 1 H2O 1 CO2 Which ONE of the following is represented by X in the above equation? A MgCO3 B MgHCO3 C MgCO2 D Mg(OH)2 (2) 1.9 Indicate which one of the following reactions is a redox reaction: A NaCl(s) Na+(aq) 1 Cl−(aq) B 2Na(s) 1 Cl2(g) 2NaCl(s) C HNO3(aq) 1 H2O(ℓ) H3O+(aq) 1 NO3− (aq) D NaCl(aq) 1 AgNO3(aq) AgCl(s) 1 NaNO3(aq) (2) 1.10 Gold is used to coat spacecraft. The property of gold illustrated in this statement is that gold: A is a good reflector of heat B is a good conductor of heat C is a good conductor of electricity D has good ductility. (2) [20] E X E M P L A R E X A M PA P E R S 69

Section B Instructions and information 1. Start EACH question on a NEW page in the ANSWER BOOK. 2. Leave ONE line between each sub-question, for example between QUESTION 2.1 and QUESTION 2.2. 3. Show ALL formulae and substitutions in ALL calculations. 4. Round off your FINAL numerical answers to a minimum of TWO decimal places. 5. Give brief motivations, discussions, etc. where required. Question 2 Water is an important compound, and life on Earth would not have been possible without its unique properties. 2.1 Name the type of chemical bond formed between the hydrogen and oxygen atoms in water. (1) 2.2 How many valence electrons does an oxygen atom have? (1) 2.3 Write down the Lewis structure for the water molecule. (2) 2.4 Draw a diagram of the water molecule showing the atoms and the polarity of the molecule. (3) 2.5 Name the shape of the molecule. (1) A water molecule forms an oxonium ion in an acid–base reaction. 2.6 Represent the formation of the oxonium ion using Lewis structures. (4) 2.7 Name the type of bond that forms between the water molecule and a hydrogen ion. (1) An oxygen atom can also bond with another oxygen atom to form an oxygen molecule. 2.8 Write down the Lewis structure for an oxygen molecule. (2) 2.9 Which one of the following bonds will be the strongest? Give a reason for your answer. A The bond between a hydrogen atom and an oxygen atom B The bond between an oxygen atom and an oxygen atom. (2) 2.10 Hydrogen bonds exist between water molecules in the liquid phase. Discuss how these forces contribute to preserving aquatic life at the poles. (2) [19] 70 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 3 The boiling points of the hydrides of the Group 16 elements are shown in the table below. Hydride Boiling point (°C) H20 100 H 2S −60 H2Se −41 H2Te −2 3.1 Explain why the boiling point of H2Te is higher than that of H2Se. (3) 3.2 Explain why the boiling point of H2O is higher than that of H2S. (2) [5] Question 4 The table below lists the melting and boiling points of different substances at standard pressure. Substance Melting point (°C) Boiling point (°C) NaCl 800 1 413 CCl4 −23 77 HCl −114 −85 CH4 −184 −162 NH3 −78 −33 CO2 Sublimises at −79 4.1 Name the type of Van der Waals forces between molecules of: 4.1.1 HCl (1) 4.1.2 CCl4. (1) 4.2 Write down the name of the substance: 4.2.1 with the weakest intermolecular forces (1) 4.2.2 that forms hydrogen bonds between molecules. (1) 4.3 Name the force that exists between the particles when NaCl dissolves in water. (1) 4.4 Which one of the substances is a liquid at −10 °C? (1) 4.5 Which substance has non-polar molecules but polar covalent bonds between the atoms? (1) 4.6 Name the shape of the following molecules according to the VSEPR theory. 4.6.1 CH4 (1) 4.6.2 NH3 (1) [9] E X E M P L A R E X A M PA P E R S 71

Question 5 A researcher investigates the relationship between the pressure and volume of tetrachloromethane gas (CCl4) at a temperature of 400 °C. She tables the results as follows: Result P (kPa) V (cm3) A 15 160 B 20 120 C 25 96 D 30 88 E 35 68,6 5.1 The first result is correct but one of the remaining volume readings is incorrect. 5.1.1 In which result is the volume reading incorrect? (2) 5.1.2 Calculate the correct value. (2) 5.2 The values in the table suggest a certain relationship between the pressure and volume. Name and state the gas law that relates this relationship. (3) 5.3 The researcher observes that at a very high pressure the volume reading is greater than predicted by this relationship. Give a reason for this observation. (2) 5.4 When the temperature is decreased considerably, a phenomenon is observed that gives evidence of the existence of intermolecular forces. Name this phenomenon. (1) 5.5 Calculate the mass of CCl4 that was used in this experiment. (7) 5.6 If the same mass of oxygen gas was used instead of CCl4 gas, how would the volume of the O2 gas compare with that of the CCl4 gas at the same temperature and pressure? Write down only smaller than, the same or larger than. (2) [19] Question 6 In an experiment to determine the percentage purity of a sample of zinc, 40,87 g of an impure sample of zinc were reacted with hydrochloric acid: Zn 1 2HCl ZnCl2 1 H2 If 11,2 dm3 of H2 gas were collected at STP, calculate the percentage purity of the sample. (4) [4] 72 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 7 Nitroglycerine is a powerful explosive. Its decomposition is represented by: 4C3H5N3O9 6N2 1 12CO2 1 10H2O 1 O2 7.1 Why is an explosion such a powerful reaction? (3) 7.2 Calculate the maximum mass of O2 that can be obtained from 2,00 kg of nitroglycerine. (3) 7.3 How many O2 molecules were formed in Question 7.2? (2) 7.4 Calculate the total volume generated during the explosion in m3 at STP. (4) 7.5 Calculate the percentage yield in this reaction if the amount of O2 generated is found to be 65,55 g. (2) [14] Question 8 8 g of sodium hydroxide are dissolved in distilled water to form 250 cm3 solution. 15 cm3 of this solution neutralises 20 cm3 of a sulfuric acid solution. 8.1 Write a balanced equation for the reaction. (3) 8.2 Define the term ‘concentration of a solution’. (2) 8.3 Calculate the concentration of the sodium hydroxide solution. (3) 8.4 Calculate the concentration of the sulfuric acid solution. (4) [12] Question 9 Plants manufacture glucose through the process of photosynthesis by making use of water, carbon dioxide and sunlight. The balanced equation for this reaction is: 6CO2(g) 1 6H2O(ℓ) C6H12O6(s) 1 6O2(g) DH > 0 Animals eat the plants to supply their energy needs. The glucose is broken down during cellular respiration: C6H12O6(s) 1 6O2(g) 6CO2(g) 1 6H2O(ℓ) DH < 0 The graph below represents the change in potential energy of one of the two reactions listed above. Potential energy A B Progress of reaction 9.1 Is the process of photosynthesis an example of an exothermic or an endothermic reaction? Give a reason for your answer. (2) 9.2 Does the above graph represent the change in potential energy for photosynthesis or cell respiration? Briefly explain your answer. (3) E X E M P L A R E X A M PA P E R S 73

9.3 Label A and B on the graph. (2) 9.4 The reaction for cellular respiration is catalysed by enzymes. Explain how the enzymes will influence the reaction. (2) [9] Question 10 Consider the two acid–base reactions below and answer the questions that follow. (i) HNO3(aq) 1 H2O(ℓ) NO3− (aq) 1 H3O+(aq) (ii) H2O(ℓ) 1 NH3(aq) NH4+ (aq) 1 OH−(aq) 10.1 Define the term ‘ampholyte’ and identify the substance that acts as an ampholyte in the above reactions. (3) 10.2 Identify the conjugate acid–base pairs in equation (i) (2) 10.3 In a laboratory, one beaker contains a solution involving reaction (i) and another beaker contains a solution involving reaction (ii). A learner wants to test the solutions to determine whether they are acidic or alkaline. 10.3.1 Give the general term for any substance that can be used by the learner to test if the solutions are acidic or alkaline. (1) 10.3.2 Which one of the two solutions will have a pH above 7? Give a reason for your answer. (3) 10.4 A salt can be formed by reacting HNO3(aq) with NH3(aq). Give the name and formula of the salt. (2) [11] Question 11 Consider the following unbalanced reaction that is used to prepare brown nitrogen dioxide in the laboratory: Cu 1 HNO3 Cu(NO3)2 1 2NO2 1 2H2O 11.1 Define oxidation in terms of electron transfer. (2) 11.2 Was copper oxidised or reduced? Refer to the change in oxidation number of Cu to prove your answer. (2) 11.3 Give the name of the oxidising agent in this reaction. (1) 11.4 Balance the reaction by making use of the ion-electron method. (5) [10] 74 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 12 South Africa is a world leader in the technology of gold mining. 12.1 In which layer of the Earth does mining take place? (2) 12.2 Where in South Africa can the major gold mining activities be found? (2) The following flow diagram illustrates some of the most important steps in the recovery of gold from its ore: Gold-bearing Process Process Gold Process Pure NaAu(CN)2 ore A B precipitate C gold 12.3 Name Process A. (2) 12.4 Is gold oxidised or reduced during Process A? (1) 12.5 Use oxidation numbers to explain your answer in 12.4. (2) 12.6 Name the chemical substance that must be added during Process B. (2) 12.7 Process C indicates the smelting process that happens in a calcinating furnace. Explain the importance of this process. (2) 12.8 Name one other precious metal that is recovered as a gold-refining by- product. (1) The gold mining industry has advantages and disadvantages. 12.9 Give two reasons why the gold mining industry is so important to the South African economy. (2) 12.10 Write down two negative impacts that the gold mining industry has on the environment. (2) [18] Total 150 marks E X E M P L A R E X A M PA P E R S 75

Physics exemplar examination: Paper 1 memorandum Question 1 1.1 B (2) 1.2 D (2) 1.3 D (2) 1.4 C (2) 1.5 A (2) 1.6 A (2) 1.7 B (2) 1.8 C (2) 1.9 B (2) 1.10 A (2) [20] Question 2 2.1 A single force having the same effect as all other forces acting together. (2) 2.2.1 Magnitude of A 5 √52 1 42 5 6,40 force units (2) 2.2.2 tan θ 5 14 5 0,25 ⇒ θ 5 14,04° Direction of B: 165,96° (3) y-axis 2.3 5 4 3 Vector A 2 Vector B 1 1 2 x-axis –5 –4 –3 –2 –1 Resultant –1 5 −4 force units 270°/west (4) [11] Question 3 A 120° 60° C 34 km ABy 17 km B 45° BCy 30° 45° 76 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

ABy 5 34 sin 30° 5 17,00 km south BCy 5 17 sin 45° 5 12,02 km north Southerly component 5 17,00 km − 12,02 km 5 4,98 km south (5) [5] Question 4 4.1 The object is stationary, so Fres 5 0. (1) 4.2 15° 5 normal force of incline on crate 5 weight 5 tension in the rope (3) 4.3 15° 75° 5 6 000 N 6 000 N sin 15° 5 W 6 000 N ⇒W 5 sin 15° 5 23 182 N 23 182 N Mass of crate 1 rhino 5 9,8 N·kg−1 5 2 366 kg Mass of rhino 5 2 366 kg − 650 kg 5 1 716 kg (5) 4.4 The forces remain unchanged. The velocity is constant so there is no acceleration, and according to Newton’s Second Law there is therefore no resultant force. (3) [12] Question 5 5.1 When a net force is applied to an object, it accelerates in the direction of the net force. The acceleration is directly proportional to the net force and inversely proportional to the mass. (2) E X E M P L A R E X A M PA P E R S 77

5.2.1 Forces on car B: pulling force forward 5 600 N, frictional force backward 5 300 N 600 N − 300 N 5 mres 5 1 200 kg 5 0,25 m·s−2 forward (3) 5.2.2 fk 5 µkN fk ⇒µk 5 N and N 5 mg 300 N 5 1 200 kg 3 9,8 N·kg−1 5 0,03 (3) 5.3 5 400 N backwards (2) 5.4.1 When car A applies brakes, car B will keep on moving forward at the same velocity, according to Newton’s First Law and run into the back of car A. (2) 5.4.2 Car A and car B will experience the braking force simultaneously and avoid an accident. (1) [13] Question 6 The two blocks will move clockwise to the right. Take this direction as positive. 2 kg block: res 5m − (2 3 9,8) 5 2 ⇒ 5 2 1 19,6 4 kg block: (4 3 9,8) − 54 39,2 − (2 1 19,6) 5 4 39,2 − 19,6 ⇒ 5 6 5 3,3 m·s−2 clockwise (5) [5] Question 7 7.1 Every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. (3) 7.2 The weight of an object m1 can be determined by: mM W 5 m1g and F 5 W 5 G d1 2 mM ⇒ m1g 5 G d1 2 cancel m1 both sides M ⇒ g 5 G d2 (2) M 7.3 g 5 G d2 ⇒ d 5 √G dM2 5√ 6,67 3 10−11 N·m2·kg−2 3 6,4 3 1023 kg 3,8 m·s−2 5 3,36 3 106 m (4) 7.4 The mass will be the same, but the weight will be less on Mars than on Earth. (2) [11] 78 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 8 8.1 The refractive index is the ratio of the speed of light in air to the speed of light through the medium. (2) 8.2 Diamond is optically more dense. / Glass is optically less dense. (1) c 8.3 n5v c ⇒v5n 3 3 108 m·s−1 5 2,42 5 1,24 3 108 m·s−1 (2) 8.4.1 N Diamond 30° n 5 2,42 θr Glass n 5 1,52 (4) 8.4.2 n1 sin θ1 5 n2 sin θ2 ⇒ 2,42 3 sin 30° 5 1,52 sin θr θr 5 52,75° (3) n 1,00 8.5.1 sin θc 5 n2 sin 90° 5 2,42 3 1,0 1 θc 5 24,41° (2) 8.5.2 Light must move from an optically more dense to an optically less dense medium. The angle of incidence must be greater than the critical angle of the medium involved. (2) [16] Question 9 9.1 Diffraction is the bending or spreading of waves as they pass through a narrow opening or around obstacles. (2) 9.2 A – central bright orange broad band; B – dark band (2) 9.3 Dimmer than (1) 9.4 B (1) 9.5.1 A will be narrower; diffraction ∝ wavelength (λ). (2) 1 9.5.2 A will be broader; diffraction ∝ slit width (w) (2) E X E M P L A R E X A M PA P E R S 79

9.6 Every point in a wavefront acts as the source of secondary wavelets that spread out in all directions with the same speed as the wave. (2) [12] Question 10 10.1 A + + B (3) 10.2 The force per unit charge (2) kQ 10.3 EA 5 EB 5 r2 9 3 109 N·m2·C−2 3 50 3 10−9 C 5 (6,72 3 10−2 m)2 5 9,96 3 104 N·C−1 Both charges point away from point P. B R P A ER 5 √(9,96 3 104 N·C−1)2 1 (9,96 3 104 N·C−1)2 5 1,41 3 105 N·C−1 due east (7) [12] Question 11 11.1 The Right Hand Rule: If the solenoid is held in the right hand with the curved fingers pointing in the direction of the conventional current, the thumb points in the direction of the north pole of the solenoid. (3) 11.2.1 The magnitude of the emf induced in a conductor is equal to the rate of change of magnetic flux through it. (2) ∆Φ (B − Bi)A cos 0° 11.2.2 « 5 −N ∆t 5 −N f ∆t (0,10 T − 0,50 T) 3 2,0 3 10–4 m2 5 −2 100 0,12 s 5 1,4 V (5) [10] 80 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 12 12.1 Temperature (1) 12.2 The current through the resistor increases if the potential difference across it is increased. (2) 12.3 Potential difference is directly proportional to current. (1) V 1,5 V 12.4 R 5 I 5 0,06 A 5 25 Ω (3) 12.5 I (A) 0,4 light bulb 0,3 0,2 resistor 0,1 0 V (V) 0,1 0,2 0,3 0,4 0,5 (4) 12.6 The resistor is an ohmic conductor. For an ohmic conductor, I must be directly proportional to V, which is the case with the resistor. (1) 12.7 The resistor (1) [13] Question 13 1 1 1 1 13.1 R 5 R 1 R 1 … 1 R P 1 2 5 1 1 1 1 1 5 1 5 15 1 15 1 15 1 15 1 15 5 15 5 3 ∴RP 5 3 Ω (3) V2 (12 V)2 13.2 P 5 R 5 3 Ω 5 48 W (2) 1 13.3 Lesser; the total resistance will increase, while V is still 12 V. P ∝ R (2) 13.4 The total resistance changes to 5 Ω and hence the power decreases 5Ω by a factor of 3 Ω 5 1,67. (3) [10] Total 150 marks E X E M P L A R E X A M PA P E R S 81

Physics exemplar examination: Paper 2 memorandum Question 1 1.1 B (2) 1.2 D (2) 1.3 C (2) 1.4 C (2) 1.5 B (2) 1.6 C (2) 1.7 D (2) 1.8 A (2) 1.9 B (2) 1.10 A (2) [20] Question 2 2.1 (Polar) covalent bond (1) 2.2 Six (1) 2.3 HO (2) H 2.4 d– Ammonia Ammonium ion O + H H HHN  ••  + H+ H HN H   d+ d+ (3) H H 2.5 Bent (1) 2.6 Water Water Oxoniumion Oxonium ion + H H Oxygen  Hydrogen cyanide  H O + H+ •• HO H O••2 Oxygen HCN•• Hydrogen cyanide (4) 2.7 Coordinate O O •• O •• •• covalent bond / dative •• H C N HCN 2 covalent bond •• ••• ••• •• (1) or 2.8 O •• O •• or O O HC  •• N  •• •• •• •• H C N •• ••• ••• •• (2) or 2.9 B; a double bond OOis stronger than •• HCa single  N•• bond. •• (2) 2.10 The density of ice is less than that of very cold liquid water and ice floats on the water, forming an insulating layer between the water and the atmosphere and thereby preserving aquatic life under the ice. (2) [19] 82 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

Question 3 3.1 H2Te has a higher molecular mass than H2Se. Intermolecular forces increase as molecular size increases, therefore more energy is needed to change the phase from liquid to gas. (3) 3.2 H2O molecules have strong hydrogen bonds between them compared to the weak Van der Waals forces (dispersion forces) between molecules of H2S. More energy is needed to overcome the hydrogen bonds and change the phase of water. (2) [5] Question 4 4.1.1 Dipole–dipole forces (1) 4.1.2 Induced dipole forces / dispersion forces (1) 4.2.1 Methane (1) 4.2.2 Ammonia (1) 4.3 Ion–dipole forces (1) 4.4 CCl4 (1) 4.5 CO2 (1) 4.6.1 Tetrahedral (1) 4.6.2 Trigonal pyramidal (1) [9] Question 5 5.1.1 PAVA 5 15 kPa 3 160 cm3 5 2 400 kPa·cm3 5 PBVB 5 PCVC 5 PEVE PDVD 5 30 kPa 3 88 cm3 5 2 640 kPa·cm3 The reading at D is wrong. (2) 5.1.2 PDVD 5 30 kPa 3 VD 5 2 400 kPa·cm3 2 400 kPa·cm3 ⇒ VD 5 30 kPa 5 80 cm3 (2) 5.2 Boyle’s Law: The volume of a fixed amount of gas is inversely proportional to the pressure on the gas if the temperature remains constant. (3) 5.3 At high pressure the volume of the gas particles contribute to the total gas volume. (2) 5.4 Liquification (1) 5.5 P 5 15 kPa 5 15 3 103 Pa; V 5 160 cm3 5 160 3 10−6 m3; T 5 273 1 400 5 673 K; R 5 8,31 J·K−1·mol−1; n 5 ? PV 5 nRT PV ⇒ n 5 RT 15 3 103 Pa 3 160 3 10−6 m3 5 8,31 J·K−1·mol−1 3 673 K 5 4,3 3 10−4 mol E X E M P L A R E X A M PA P E R S 83

M(CCl4) 5 12 1 4(35,5) 5 154 g·mol−1 m n5 M ⇒ m 5 nM 5 4,3 3 10–4 mol 3 154 g·mol−1 5 0,066 g (7) nRT mRT 5.6 Larger than (V 5 P 5 MP ; M(O2) < M(CCl4) \ V(O2) > V(CCl4)) (2) [19] Question 6 1 mol Zn releases 1 mol H2 65,4 g Zn releases 22,4 dm3 H2 11,2 dm3 Pure Zn: 22,4 dm3 3 65,4 g 5 32,7 g 32,7 g Percentage purity 5 40,87 g 3 100 5 80% pure (4) [4] Question 7 7.1 The reaction is very exothermic and generates a large amount of heat and many molecules in the gas phase so that there is a massive increase in volume. (3) 7.2 908 g C3H5N3O9 yield 32 g O2 2 000 g 2 000 g C3H5N3O9 yield 908 g 3 32 g 5 70,48 g O2 (3) 70,48 g 7.3 Number of O2 molecules 5 32 g 3 6,02 3 1023 5 1,33 3 1024 (2) 7.4 908 g C3H5N3O9 yield 29 mol gas 2 000 g 2 000 g C3H5N3O9 yield 908 g 3 29 mol 5 63,88 mol gas Volume: 63,88 mol 3 22,4 dm3·mol−1 5 1 430,9 dm3 or 1,43 m3 (4) 65,55 g 7.5 Percentage yield 5 70,48 g 3 100 5 93% (2) [14] Question 8 8.1 2NaOH 1 H2SO4 Na2SO4 1 2H2O (3) 8.2 The amount of solute (dissolved substance) per cubic decimetre of solution (2) m 8.3 c 5 MV 8g 5 40 g·mol−1 3 0,25 dm3 5 0,8 mol·dm−3 (3) 8.4 nNaOH 5 cV 5 0,8 mol·dm−3 3 0,015 dm3 5 0,012 mol 2 mol NaOH react with 1 mol H2SO4, so 0,006 mol H2SO4 reacted 84 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1

n c5V 0,006 mol 5 0,02 dm3 5 0,3 mol·dm−3 (4) [12] Question 9 9.1 Endothermic; DH is greater than zero / positive. (2) 9.2 Photosynthesis; during endothermic reactions more energy is absorbed than released. (3) 9.3 A: activation energy; B: enthalpy change (2) 9.4 Enzymes increase the reaction rate by lowering the activation energy. (2) [9] Question 10 10.1 An ampholyte is a substance that can act as either an acid or a base. H2O (3) 10.2 Acid 1: HCl; conjugate base 1: Cl− Base 2: H2O; conjugate acid 2: H3O+ (2) 10.3.1 Indicator (1) 10.3.2 Solution (ii); NH3 is a base and forms OH− ions in solution, which increases the pH. (3) 10.4 Ammonium nitrate; NH4NO3 (2) [11] Question 11 11.1 Oxidation is the loss of electrons. (2) 11.2 Oxidised. Cu: 0; Cu in Cu(NO3)2: 12; the oxidation number increased (2) 11.3 Nitric acid (1) 11.4 Cu Cu2+ 1 2e− Add H2O and H+ to balance the number of atoms: 2H+ 1 NO3 − 1 e− NO2 1 H2O Multiply the second reaction by 2 to balance electrons. Ionic equation: Cu 1 4H+ 1 2NO3 − Cu2+ 1 2NO2 1 2H2O (5) [10] E X E M P L A R E X A M PA P E R S 85

Question 12 12.1 The crust (2) 12.2 The Witwatersrand basin (2) 12.3 Cyanidation (2) 12.4 Oxidised (1) 12.5 Au(0) in gold ore changes to Au(1) in NaAu(CN)2 – the oxidation number increases from 0 to 11. (2) 12.6 Zinc powder (2) 12.7 Gold is smelted at high temperatures to remove impurities. (2) 12.8 Silver (1) 12.9 Creates jobs / a lot of money can be generated from gold resources / the economy of the country grows (2) 12.10 Destruction of natural ecosystems / moving of people from areas where they have lived for a long time / mining can make the surrounding land unstable and unsafe to build on / pollution as a result of energy needed for the extraction of the metal / destruction of the surrounding landscape / cyanide can pollute water and become a threat to aquatic life / waste water can dissolve sulfur compounds causing acid mine drainage water (2) [18] Total 150 marks 86 S T U DY & M A S T E R P H Y S I C A L S C I E N C E S S U P P O R T PA C K G R A D E 1 1