Cambridge IGCSE Design and Technology 0445 — 2013 May/June Paper 4 · Variant 2

[Turn over *0699650741* READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fl uid. DO NOT WRITE IN ANY BARCODES. You may use a calculator. Section A Answer all questions. Section B Answer one question. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A Section B Total DESIGN AND TECHNOLOGY 0445/42 Paper 4 Systems and Control May/June 2013 1 hour Candidates answer on the Question Paper. No Additional Materials are required. To be taken together with Paper 1 in one session of 2 hours and 15 minutes. UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certifi cate of Secondary Education This document consists of an 17 printed pages and 3 blank pages. [Turn over IB13 06_0445_42/FP © UCLES 2013

2 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use Section A Answer all questions in this section. 1 Fig. 1 shows two circuit symbols. Add the name of the component to each symbol. M … … Fig. 1 [2] 2 Complete Fig. 2 to show how the two components can be connected to give a resistance of 5 kΩ between points A and B. A B 10 kΩ 10 kΩ Fig. 2 [2] 3 (a) Name the switch arrangement shown in Fig. 3. … … … … Fig. 3 [1] (b) Add labels to Fig. 3 to indicate the normally closed (NC) and normally open (NO) terminals. [2] 4 Give two examples of natural structures that will resist tension. 1 … 2 … [2]

3 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use 5 Complete the table below by adding a tick () to show which forces the materials are best at resisting. Only add one tick () for each material. materials tension compression bending concrete steel cable laminated wooden beam [3] 6 Fig. 4 shows the framework for a set of shelves used to carry heavy loads in a storage unit. Use notes and sketches to show two methods of making the framework more rigid when the shelves are loaded. Fig. 4 [2] 7 Give two advantages of using roller bearings to support an axle compared to plain bearings. 1 … 2 … [2]

4 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use 8 (a) Fig. 5 shows a drawing of a cam. Indicate the part of the cam that will provide ‘dwell’. Fig. 5 [1] (b) Describe the conversion of motion provided by a cam and follower. … … [2] 9 Fig. 6 shows a crank lever, chain ring and pedal from a bicycle. Add labels to show effort, load and fulcrum. Fig. 6 [3]

5 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use 10 Fig. 7 shows two views of a wheelbarrow loaded with bricks. X Fig. 7 Y (a) State the order (class) of lever which is used in a wheelbarrow. … [1] (b) Explain why method X is a more effi cient way of loading the wheelbarrow in Fig. 7 than method Y. … … … [2]

6 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use Section B Answer one question from this section. 11 (a) Fig. 8 shows a model beam set up for testing defl ection. Use notes and sketches to show how the defl ection of the beam can be accurately measured. load beam 120 benchtop Fig. 8 [4] (b) (i) Explain the term factor of safety with reference to structures. … … … … [3] (ii) When a road bridge is being designed give three features that may be considered when calculating the factor of safety. 1 … 2 … 3 … [3]

7 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (c) Fig. 9 shows a bridge supporting the weight of a lorry. A D 10 m 10 m 3 m B 65 kN C 100 kN Fig. 9 Calculate the reactions at A and D. … … … … [4] (d) Fig. 10 shows three different methods of joining metals used in a structure. Give a different reason for using each method. nut and bolt rivet welded joint Fig. 10 nut and bolt … rivet … welded joint … [3]

8 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use (e) (i) Wooden framing is often used in the construction of houses as shown in Fig. 11. Fig. 11 Give two reasons why wood is a suitable material for a house framework. 1 … 2 … [2] (ii) Fig. 12 shows two lengths of wood to be used as fl oor beams. Y X Fig. 12 Explain why the beam should be placed as shown in position Y rather than position X. … … [2]

9 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (iii) Describe two defects in a length of wood that should be avoided when selecting the wood for use in a structure. 1 … 2 … [2] (f) Describe the difference between a strut and a tie in a framework. … … … [2]

10 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use 12 (a) Fig. 13 shows two views of a car foot pump. Fig. 13b Fig. 13a (i) Mark on Fig. 13b the position of three points that will pivot when the foot pump is operated. [3] (ii) Give one reason for using grease rather than oil to lubricate the pivot points. … [1] (iii) The action of the foot pump includes a conversion of motion. Complete the sentence below. … motion is converted to … motion when the foot pump is used. [2] (iv) Explain why the actual Mechanical Advantage achieved by the foot pump is less than the calculated Mechanical Advantage. … … … [2]

11 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (b) Fig. 14 shows the drive mechanism on a bicycle. chain rings rear sprockets Fig. 14 (i) Give two reasons for using a chain drive rather than a belt drive to transmit motion on a bicycle. 1 … … 2 … … [2] (ii) The bicycle has 3 chain rings and 8 sprockets at the rear wheel. State the number of gear ratios available. … [1] (iii) Calculate the Velocity Ratio when a 52 teeth chain ring and 18 teeth rear sprocket are used. … … [2] (iv) Bearings are used on all of the moving parts of a bicycle. Explain why ball bearings would be used on the chain ring axle. … … … [2]

12 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use (v) gear change mechanism Fig. 15 State the two functions of the gear change mechanism shown in Fig. 15. 1 … 2 … [2] (c) (i) State three types of power source that can be used to operate a mechanism. 1 … 2 … 3 … [3] (ii) Explain how improving the design of a mechanism can reduce the energy required to operate the mechanism. … … … … [3]

13 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (d) Fig. 16 shows two views of a clamping device that uses a ratchet and pawl to hold the jaws closed. A release trigger will allow the clamp to open. Fig. 16 Use notes and sketches to show one other use of a ratchet and pawl mechanism. [2]

14 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use 13 (a) When building a circuit the components have to be matched to their symbol or description. (i) Complete Fig. 17 by matching the component to the symbol or description. One has been done for you. 1 1 2 3 4 relay capacitor fixed resistor 5 100 n Fig. 17 [4] (ii) The list below gives component values available for a time delay circuit. capacitor values 100 nF 2200 pF 470 µF 100 µF 330 nF resistor values 100 Ω 2 MΩ 270 kΩ 6.8 Ω 1.5 kΩ State the values of the two components that will give the longest delay. … … [2] (iii) When using an integrated circuit (IC) it is important to know the pin numbers. Complete Fig. 18 to show the numbers of the two pins indicated on the 8 pin IC. Fig. 18 [2]

15 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (b) A warning device is required to indicate when the temperature falls below a set level. The circuit shown in Fig. 19 is based on a 555 timer IC. When it has triggered, the warning LED will remain lit until the 555 timer resets. 7 4 8 1 5 6 3 2 555 + +9 V 0 V A X Fig. 19 (i) Describe the purpose of component A. … [1] (ii) Calculate the voltage at point X when component A is set at 40 kΩ and the thermistor resistance is 3 kΩ. Use the potential divider formula Vout = R R R + 2 2 1 × Vin … … … [2] (iii) A transistor switch is used between point X and pin 2 of the timer. Complete the circuit in Fig. 19 to show the transistor switch connected. [3]

16 0445/42/M/J/13 © UCLES 2013 For Examiner’s Use (c) When the circuit is built and tested, it triggers after 7 minutes 30 seconds and the LED remains on for 10 minutes. (i) Complete Fig. 20 to show the graph of the 555 timer output. 9 6 3 0 0 5 10 15 minutes Fig. 20 volts 20 25 [2] (ii) The time for the LED to stay on had been calculated as 8 minutes. Explain why the actual output time of 10 minutes does not match the calculated time. … … [2] (d) A multimeter is to be used to measure the current fl ow in the circuit. Complete Fig. 21 to show: ● the correct setting on the multimeter dial; ● the correct connections to the circuit and battery. AC V DC V OFF OFF 10 A mA µA Ω V Ω mA COM battery –V +V +V 0 V circuit board Fig. 21 [3]

17 0445/42/M/J/13 © UCLES 2013 [Turn over For Examiner’s Use (e) A circuit for a short time delay can be made from logic gates as shown in Fig. 22. trigger output +V 0 V A B Q A 0 0 1 1 B 0 1 0 1 Q Fig. 22 (i) State the name of the logic gate used in the circuit. … [1] (ii) Complete the truth table in Fig. 22 for the type of logic gate used. [1] (iii) One of the logic gates has both inputs joined. Describe the effect of this on the output of the logic gate. … … … [2]

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20 0445/42/M/J/13 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. BLANK PAGE © UCLES 2013

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2013 series 0445 DESIGN AND TECHNOLOGY 0445/42 Paper 4 (Systems and Control), maximum raw mark 50 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

Page 2 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 Section A 1 (a) 1 mark for each correct symbol, 2 × 1. [2] 2 10kΩ resistors connected in parallel [1], correct connections to A and B. [1] [2] 3 (a) Switch arrangement is single pole double throw / SPDT, 1 mark. [1] (b) Correct labels [1]. [2] 4 Examples could include: Bones in skeleton, tree branches, spiders web or any other that will resist tension, 2 × 1 marks. [2] 5 One mark for each correct, 3 × 1 marks. [3] 6 Strengthening should be in the form of triangulation, struts, ties, gusset plates. One mark for two different methods or one mark each for the same method resisting loads in different directions 2 × 1 marks. [2] 7 Advantages of roller bearings could be: • reduced friction between surfaces • can carry higher load • lower cost in replacement • more durable at high speed • Can be sealed for life, requiring less lubrication Allow any other valid benefit 2 × 1 marks. [2] materials tension compression bending concrete
steel cable
laminated wooden beam
M motor [1] LDR [1] NC NO 10kΩ 10kΩ A B

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 8 (a) Indication on the lower half of cam profile 1 mark. [1] (b) Rotary to reciprocating one mark for each correct term. [2] 9 One mark for each correct label 3 × 1. [3] 10 (a) The wheelbarrow is a class 2 lever, 1 mark. [1] (b) The load is moved closer to the fulcrum. [1] This will increase the efficiency / mechanical advantage of the lever. [1] The load is more stable against the front of the barrow. [1] Give marks for any two correct points in description. Accept reasons for not choosing method Y. [2] [Total: 25] effort load fulcrum

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 Section B 11 (a) Dial gauge shown or described. [1] Probe of dial gauge placed centrally under beam. [1] Dial gauge supported in a suitable way. [1] Dial gauge adjusted to read zero before test. [1] Description of gauge movement as beam deflects. [1] Any four of above 4 × 1 marks. Allow other valid points. No marks for use of a ruler. [4] (b) (i) The following points may be included: • Factor of safety is the structural capacity beyond the expected load • How much stronger is the structure than the expected load • Ratio of maximum strength to the intended design load Explanation that includes two justified relevant points 3 marks. Only one justified point mentioned 2 marks. Some understanding shown 1 mark. [3] (ii) The following features of a road bridge could be considered: • Maximum amount of vehicles on bridge at any one time • Dynamic loads caused by weather conditions • Potential movement of ground supporting the structure • Increase in weight of HGVs in the future • Choice of materials used Allow any other valid feature, 3 × 1 marks. [3] (c) Take moments about A (65 × 10) + (100 × 13) – RD × 23 = 0 [1] RD = (650 + 1300) / 23 = 84.78kN [1] RA + RD = 165kN [1] RA = 165 – 84.78 = 80.22kN [1] Allow 4 marks if correct answer with no working. [4] (d) Nut and bolt, no heat involved, can be removed if necessary, [1] Rivet, permanent method can be either hot or cold process, [1] Welded joint, permanent method, strong, flush surface, [1] Allow any other valid reasons. [3]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 (e) (i) Reasons could include: • Renewable resource can come from a managed forest • Durable, particularly when protected • Strong in tension and compression (‘strong’ must be qualified) • Will allow movement in foundations without losing strength • Easily worked and can be prepared off site in controlled conditions 2 × 1 marks for any suitable reasons. [2] (ii) Increased width compared to thickness will resist bending better. [1] Fewer supports will be needed, saving on timber. [1] The beam can span a greater distance safely. [1] [2] (iii) Defects could include, splits, shakes, knots, warping, insect damage or any other valid defect, 2 × 1 marks. [2] (f) A strut will resist compression. [1] A tie will resist tension. [1] [2] Allow marks for understanding shown. [Total: 25]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 12 (a) (i) One mark for each pivot point correct, 3 × 1. [3] (ii) Grease will not run off the pivot points as quickly as oil. Foot pump may be used infrequently so lubrication with grease will last longer, 1 mark for suitable response. Allow any other valid reasons. [1] (iii) Oscillating motion is converted to reciprocating motion. 2 × 1 marks. [2] (iv) Explanation to mention frictional losses at pivot points in both axial and thrust. Losses in the piston rod movement and in air moving out of pump. Air tube and cylinder will heat in use; some energy is converted to heat. 2 marks for justified explanation. [2] (b) (i) Reasons for using a chain drive include: • Only a small amount of stretching takes place in the chain • Positive drive will not slip • Long lasting and works well in adverse weather conditions Allow any other valid reasons. [2] (ii) 24 gear ratios available. [1] (iii) Velocity ratio = 52 / 18, 1 mark = 2.89:1, (accept 2.88, 2.9) 1 mark. Allow 2 marks for answer with no working. [2] (iv) Reasons for ball bearing use will include: • Ball bearings will reduce the contact area between axle and bearing race (reduce friction) • Easily replaceable for maintenance • Ball bearings will also deal with thrust where a roller bearing will not Two factors mentioned and justified, 2 marks. Allow 2 marks for one factor fully explained. [2] (v) Moving the chain across the sprockets to change gear. [1] Tensioning the chain. [1] [2] pivot pivot pivot

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 (c) (i) Power sources will include: • Mains electricity • Battery power • Chemical • Pneumatics (air) • Hydraulics (oil) • Water, wind, and other renewable sources • Human power Accept other valid answers. 1 mark for each correct, 3 × 1. [3] (ii) Improvements to a mechanism could include: • Reducing weight, this will reduce friction in moving parts • Using appropriate materials modern, lightweight, e.g. carbon fibre • Reducing the number of parts • Improved bearings on moving parts Two relevant points with justified explanation for 3 marks. One point with clear explanation, 2 marks. One / two relevant points with no further explanation, 1 mark. [3] (d) 1 mark for ratchet and pawl mechanism shown or described. 1 mark for a valid use, which could be: • Mechanical clock / watch winder • Ratchet screwdriver • Socket set wrench • Cable clamps • Handcuffs • Electrical ties (zip ties) 2 × 1 marks. [2]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 13 (a) (i) 4 × 1 marks. [4] [2] (ii) Capacitor 470µF, 1 mark Resistor 2MΩ, 1 mark. [2] (iii) 2 × 1 marks for correct pin labels. [2] (b) (i) VRI is to adjust the sensitivity of the trigger / form a potential divider with the thermistor / alter the trigger point of the IC. Allow mark for understanding shown. [1] (ii) Substitution into formula Vout = (3K / (3K + 40K) × 9 [1] Vout = (3 / 43) × 9 = 0.628V [1] Allow 2 marks for correct answer with no working. [2] (iii) Symbol(s) correct [1] allow direct connection of base to X. Pull up resistor used [1] Connection to pin 2 [1] [3] 4 1 5 3 2 1 8 X R C1 VR1 [1] [1] [1]

Page 9 Mark Scheme Syllabus Paper IGCSE – May/June 2013 0445 42 © Cambridge International Examinations 2013 (c) (i) Correct shape going from 0V to +9V and returning to 0V. [1] Pulse to start at 7.5m and continue for 10m. [1] [2] (ii) Tolerance on value of capacitor or resistor. [1] This will affect the total time delay produced. [1] Explanation must include reference to the component tolerance for marks. [2] (d) Dial setting mA, [1] Battery negative to circuit 0V, [1] positive through meter. [1] Multimeter may be inserted into the negative line. [3] (e) (i) The logic used is NOR, 1 mark. [1] (ii) Truth table output correct, 1 mark. [1] (iii) Joining the inputs forces the same logic level on both input gates. [1] The result is that the output for the gates is opposite to the input. [1] This gives a NOT gate or inverter. [1] 2 × 1 marks for any two of above statements included in desciption. [2] 0 5 10 15 20 25 3 6 9 volts minutes Ω V mA COM DC V OFF AC V Ω OFF 10A mA A µ +V 0V +V -V circuit boa battery [1] [1] [1] A B Q 0 0 0 0 1 1 1 1 1 0 0 0