Cambridge A Level Physics 9702 — 2009 Oct/Nov Paper 3 · Variant 3

This document consists of 8 printed pages and 4 blank pages. DC (SHW 00445 4/09) 13783/3 © UCLES 2009 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level 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, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer both questions. You will be allowed to work with the apparatus for a maximum of one hour for each question. You are expected to record all your observations as soon as these observations are made, and to plan the presentation of the records so that it is not necessary to make a fair copy of them. The working of the answers is to be handed in. Additional answer paper and graph paper should be submitted only if it becomes necessary to do so. You are reminded of the need for good English and clear presentation in your answers. At the end of the examination, fasten all your work securely together. All questions in this paper carry equal marks. * 2 4 2 1 3 6 6 7 2 6 * PHYSICS 9702/33 Paper 31 Advanced Practical Skills 1 October/November 2009 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. For Examiner’s Use 1 2 Total

9702/33/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use You may not need to use all of the materials provided. 1 In this experiment, you will investigate the extension of one of the springs supporting a load as the load is varied. The apparatus has been partly assembled. Complete the assembly by suspending the mass hanger (with no masses on it) from the central loop, as shown in Fig. 1.1. marks 0.100 m apart v l mass hanger spring A spring B Fig. 1.1 Note that two marks 0.100 m apart have been made on the string. (a) Record the suspended mass M (the mass of the mass hanger). M = … kg (b) (i) Measure the length l of the coiled section of spring A, as shown in Fig. 1.1. l = … m (ii) Hence calculate the extension x of the spring (the unloaded length is written on a card). x = … m (c) Measure the heights of the marks above the bench and use these to find the vertical separation v of the marks (see Fig. 1.1). Show your working. v = … m 3

4 9702/33/O/N/09 © UCLES 2009 For Examiner’s Use (d) Add more mass to the hanger and repeat (a), (b) and (c) until you have six sets of readings for M, l, x and v. Include values of M v in your table. (e) (i) Plot a graph of M v on the y-axis against x on the x-axis. (ii) Draw the line of best fit. (iii) Determine the gradient and y-intercept of the line of best fit. gradient = … y-intercept = …

5 9702/33/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use

6 9702/33/O/N/09 © UCLES 2009 For Examiner’s Use (f) The quantities M, v and x are related by the equation M v = qkx + qC where q is a constant, k is the spring constant (the value of k is written on a card) and C is the tension required for the initial separation of the spring’s coils. Using your answers from (e)(iii), determine the value of C. C = … N

7 9702/33/O/N/09 [Turn over BLANK PAGE Please turn over for Question 2.

8 9702/33/O/N/09 © UCLES 2009 For Examiner’s Use You may not need to use all of the materials provided. 2 In this experiment, you will investigate how the frictional force between a wooden rod and nylon thread varies with the length of thread in contact with the rod. (a) Use the vernier calipers to determine the diameter d of the wooden rod. Show all your working. d = … (b) Estimate the percentage uncertainty in d. percentage uncertainty = … (c) Assemble the apparatus as shown in Fig. 2.1. The 10 g mass is already attached to one end of the thread. Attach the 50 g mass hanger to the other end. mass hanger 10 g mass wooden rod stand and clamp Fig. 2.1 The thread is wrapped 1.5 times around the rod. The turns of thread must not touch each other. (d) Use your value from (a) to calculate the length l of thread in contact with the rod. (Circumference of rod = d). Show all your working. l = …

9 9702/33/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use (e) Add masses to the hanger until the hanger just starts to move down to the bench. Record this mass m (including the mass of the hanger). m = … g (f) Remove the masses from the hanger and then wrap the thread one more time around the rod, so that it is now wrapped around the rod 2.5 times. Repeat steps (d) and (e). l = … m = … (g) It is suggested that m and l are related by the equation m 2 = kl 3 where k is a constant. By calculating values of k, explain whether your results support this relationship. … … … …

10 9702/33/O/N/09 © UCLES 2009 For Examiner’s Use (h) (i) State and explain four sources of error or limitations of the procedure in this experiment. 1. … … 2. … … 3. … … 4. … … (ii) Suggest and explain four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures. 1. … … 2. … … 3. … … 4. … …

12 9702/33/O/N/09 BLANK PAGE 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.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2009 question paper for the guidance of teachers 9702 PHYSICS 9702/33 Paper 33 (Advanced Practical Skills 1), maximum raw mark 40 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 must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the October/November 2009 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9702 33 © UCLES 2009 1 (b) (i) Value for l between 0.010 and 0.080 m (1.0–8.0 cm), or ± 2.0 cm of supervisor’s value. Raw value(s) to nearest mm. [1] (c) Two values of height given. [1] Check calculation. Ignore POT error. If method incorrect to work out v, final (f) mark not available. [1] (d) No help from supervisor. [1] Six sets of values scores 3 marks, five sets scores 2 marks etc. [3] Add up number of sets of readings for M and l and put a ringed total by the table. Wrong trend –1 (Correct trend M increases, l increases). Range of M includes 100 g or 150 g and 400 g or 450 g. [1] Each column heading must contain a quantity and a unit where appropriate. [1] Ignore units in the body of the table. There must be a distinguishing mark between the quantity and the unit. (solidus is expected, accept brackets e.g. M/kg, l/m, v/m, M/v / kg m–1) Consistency of presentation of raw readings. All values of raw l are given to the same number of decimal places. [1] Significant figures for M/v must be the same as, or one more than the least number of [1] significant figures used in M or v. Check each row. If v = constant, quality mark not available AND final (f) mark not available. Check the specified value of M/v correct. (Expect around 1–3 kg m–1 or 10–30 g cm–1) [1] Ignore POT. If incorrect write in correct value. Allow small rounding errors. Graph (e) (i) Axes [1] Sensible scales must be used. Awkward scales (e.g. 3:10) are not allowed. Scale markings should be no more than three large squares apart. Scales must be chosen so that the plotted points must occupy at least half the graph grid in both x and y directions. Allow inverted axes. Do not allow wrong graph. Scales must be labelled with the quantity which is being plotted. Ignore units. All observations must be plotted. Put a ringed total of plotted points. [1] Ring and check a suspect plot. Tick if correct. Re-plot if incorrect. Work to an accuracy of not greater than half a small square. Do not allow blobs (i.e. diameter > half a small square). (e) (ii) Line of best fit [1] Judge by scatter of points about the candidate's line. There must be a fair scatter of points either side of the line. At least 5 trend plots required. Quality. This mark is not available for the wrong graph or wrong trend. [1] Judge by scatter of all the points about a best fit line. All points in the table (of which there must be at least 5 plots) must be plotted. Allow ± 0.3 cm to scale on the x-axis. (If v = constant, quality mark not available AND final (f) mark not available.)

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9702 33 © UCLES 2009 (e) (iii) Gradient. Check dy/dx [1] The hypotenuse must be at least half the length of the drawn line on the graph grid. Read-offs must be read to at least half a small square. If read-off incorrect write in correct value. Be prepared to check both read-offs. If both incorrect do not allow ecf in the y-intercept if using one of the read-offs from the gradient. Intercept. Check substitution only. Check both read-offs to half a small square. [1] or read from graph to half a small square as long as no false origin. (f) Look for values of y-intercept and gradient used correctly to find C. [1] i.e. grad = qk AND y-intercept = qC or y-intercept = (grad/k) × C. Value of C in range 0 to ± 1 N, consistent with unit or refer to supervisor’s results. [1] Correct method needed. If method of working out v incorrect or if v = constant in table, this mark is not available. [Total: 20] 2 (a) Evidence of repeat measurements of d. [1] Value of raw d(s) given to nearest 0.1 mm or 0.01 mm (–1 if help given by supervisor). [1] (b) Percentage uncertainty in d. [1] If repeated readings have been done then the uncertainty could be half the range, otherwise absolute uncertainty must be 0.1 mm or 0.01 mm consistent with above. Correct ratio idea required. (d) Method of calculation of l correct. 1.5πd [1] Significant figures in l same or one more than the raw values of d. Ignore units. [1] (e) Value of m1 in range 60 to 300 g, consistent with unit. [1] If Supervisor notes that hanger moved at 50 g allow m1 = 50 g. (f) Evidence of repeat readings for first or second value of m. [1] Second value of m. [1] Second value of l greater than first l. [1] Second value of m ≥ 2 × m1. [1] (g) Calculation of the two values of m2 / l3 or equivalent. Check one value and correct substitutions. [1] Conclusion consistent with candidate’s k values. Use 20% permitted variation in k if candidate does not suggest a value. [1]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9702 33 © UCLES 2009 (h) (i) and (ii) Sources of error or limitation. [4] Improvements. Use of other apparatus or different procedures. [4] Ap Only two readings/Two readings are not enough (to draw a valid conclusion). As Take many (sets of) readings and plot a graph/find more values of k’s. Be clear NOT just repeat readings. Bp Circumference/l imprecise because helical/coiled/slanted/spiral/thickness of thread/non-uniform diameter of rod. Bs Mark string and measure length/wrap so coils are closer/allow for thickness of thread/ diameter to be taken at different places along/diameter taken at different angles (at same position). Cp Use of (10 g) increments imprecise. Cs Use smaller mass increments/use newtonmeter/other valid method (water or sand). Dp Difficulty to judge/tell when the string starts to slip/gradual movement. Ds Practical method of detecting movement: fixed marker or scale/motion sensor/(travelling) microscope/measure height from table. Ep Large scatter in repeated readings of mass/non-uniform surface bar/varying friction. Es Fp Difficult to add masses without swinging/pushing the hanger/masses do not fit hanger. Fs Lower masses slowly/support underneath and remove hand slowly/scissor jack. Ignore reference to light gates, video, reaction time, repeat readings, micrometer, fans, parallax or sanding. [Total: 20]