Cambridge A Level Physics 9702 — 2008 Oct/Nov Paper 3 · Variant 2

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. This document consists of 8 printed pages and 4 blank pages. (KN) T43993/4 © UCLES 2008 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level * 9 4 5 0 0 3 2 5 3 4 * CANDIDATE NAME CENTRE NUMBER CANDIDATE NUMBER PHYSICS 9702/32 Paper 32 Advanced Practical Skills 2 October/November 2008 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. For Examiner’s Use 1 2 Total

3 9702/32/O/N/08 [Turn over © UCLES 2008 You may not need to use all of the materials provided. 1 In this experiment you will investigate the equilibrium position of a pivoted wooden strip as the turning load on it is varied. (a) The equipment is set up as shown in Fig. 1.1. (i) Add sand to the plastic container until the angle θ is between 5° and 10°. θ B plastic container sand plumb line Fig. 1.1 (ii) Measure and record the value of θ. θ = … ° For Examiner’s Use

4 9702/32/O/N/08 For Examiner’s Use © UCLES 2008 (b) Add n paper clips to the string loop at B and repeat (a)(ii) until you have six sets of values of n and θ, with θ in the range 5° to 60°. You may bend the paper clips if you wish. Include values of 1 –––– cosθ in your table of results. (c) Plot a graph of 1 –––– cosθ on the y-axis against n on the x-axis and draw the line of best fit. (d) Determine the gradient and y-intercept of the line. gradient = … y-intercept = …

5 9702/32/O/N/08 [Turn over For Examiner’s Use © UCLES 2008

6 9702/32/O/N/08 For Examiner’s Use © UCLES 2008 (e) The formula that relates θ and n is 1 –––– cosθ = 2 kmn + kM where k is a constant, m is the mass of one paperclip and M is the mass of the wooden strip and protractor. The value of m is written on a card. Use your answers from (d) to determine values for k and M. k = …g–1 M = …g

7 9702/32/O/N/08 [Turn over BLANK PAGE Please turn over for Question 2.

8 9702/32/O/N/08 For Examiner’s Use © UCLES 2008 You may not need to use all of the materials provided. 2 In this experiment you will investigate how the period of oscillation of a metal strip varies with its length. (a) You are provided with a metal strip with a mass fixed to it at one end. Clamp the strip between the two blocks of wood, so that the length l between the blocks and the centre of the mass is about 20 cm as shown in Fig. 2.1. clamps blocks of wood l bench Fig. 2.1 (b) (i) Measure the length l. l = …cm (ii) Estimate the percentage uncertainty in your value of l. percentage uncertainty = …% (iii) Calculate the value of l 3. l 3 = … cm3 (iv) Justify the number of significant figures you have given for l 3. … …

9 9702/32/O/N/08 [Turn over For Examiner’s Use © UCLES 2008 (c) Pull the mass about 2 cm to one side and release it so that it oscillates. Take measurements to determine the period of oscillation T. T = …s (d) Adjust the length l to about 15 cm. Measure this new length l and repeat (b)(iii) and (c). l = …cm l 3 = … cm3 T = …s (e) Explain whether your results support the idea that T 2 is proportional to l 3. … … … … …

10 9702/32/O/N/08 For Examiner’s Use © UCLES 2008 (f) (i) State four sources of error or limitations of the procedure in this experiment. 1. … … 2. … … 3. … … 4. … … (ii) Suggest four improvements that could be made to the experiment. You may suggest the use of other apparatus or different procedures. 1. … … 2. … … 3. … … 4. … …

12 9702/32/O/N/08 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 2008 question paper 9702 PHYSICS 9702/32 Paper 32 (Advanced Practical Skills 2), maximum raw mark 40 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 2008 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme Syllabus Paper GCE A/AS LEVEL – October/November 2008 9702 32 © UCLES 2008 1 (a) (ii) Measurement of θ. 5 Y θ Y 10° Ignore d.p. [1] (b) Six sets of readings scores 6 marks, five sets scores 5 marks, etc. Help given, –1 (e.g. putting plumbline into position). Generally wrong trend, –1. Allow n = 0. [6] Range. Maximum angle θ max [ 45°. [1] Table headings. θ /° θ (°) No unit for 1/cosθ. [1] Consistency in raw data – all values of θ given to the nearest 1° or 0.5°. [1] Calculated quantities. Allow small rounding errors. – check the specified value of 1/cosθ and tick if correct. Specified value is the largest value of θ. [1] Significant figures. [1] – all values of 1/cosθ should be to the same s.f. as (or one more than) the raw value of θ. Quality of data. 5 points close to Examiner’s straight line. Wrong trend/curved trend – no mark. [1] (c) Points should occupy at least half the grid in both directions and scales should be sensible (not 3, 6, 9 or other awkward) and labelled with a quantity. Do not penalise reversed axes. Label FO. Ignore units. [1] Check that one point is correctly plotted (error Y half a small square). All tabulated results to be plotted on graph grid. Do not allow blobs (points [ half a small square). If plot incorrect indicate correct position. [1] Line of best fit. At least 5 trend plots. Allow curved trend. No hairy or thick lines ([ half a small square). No kinks. [1] (d) Gradient. Triangle chosen for gradient as a hypotenuse at least half the length of the drawn line. Read-offs are on the line correct to within half a small square and correct substitution. Gradient mark = 0 if curve used. If wrong write in correct read-off. Correct sub into ∆y/∆x. [1] Intercept calculated by a correct method or using the graph. Allow for extrapolation for curve at n = 0 (i.e. do not allow algebraic errors with y = mx + c). [1] (e) Correct method and substitution. k equal to     m 2 gradient . [1] Method and value of M within 50 % of Supervisor’s value. M = intercept / k. Allow e.c.f. for k. Write in Supervisor’s value for M underneath. [1] [Total: 20]

Page 3 Mark Scheme Syllabus Paper GCE A/AS LEVEL – October/November 2008 9702 32 © UCLES 2008 2 (b) (i) Measurement of l 19.0 Y l Y 21.0 cm. Ignore d.p. Supervisor’s help –1. [1] (ii) Correct method of estimation of percentage uncertainty. ∆l = 1 mm or 2 mm or half the range. [1] (iii) Correct calculation of first value of l3 (20³ = 8000). If incorrect write in correct value. Accept small rounding errors. [1] (iv) Justification for s.f. for l3. Same or one more than the raw value of l. Consistent with their own data. [1] (c) Measurement of T. 0.2 Y T Y 2.0 s [1] (c) or (d) Measurement of raw t to the nearest 0.1 s or 0.01 s. [1] Evidence of repeat readings of t. [1] Evidence of n [ 10 oscillations. [1] (d) Measurement of second l to nearest mm. [1] Measurement of second T(d) I T(c) . Penalise wrong trend. [1] (e) Correct method and calculation of k values. [1] Valid comment on whether equation applies to results. [1] Allow e.c.f. on arithmetic errors of k values. Evidence of correct ratio for one value of k is necessary to access this mark. k values within 10% to support relationship. Allow up to 20% if candidate stated a value. (f) (i) Problems [4] (f) (ii) Improvements [4] Ap Not enough readings (to draw a conclusion). As More readings and plot a graph. Bp Time too fast/moves too fast/error in timing large compared to time measured. Bs 1 Video recorder, playback frame by frame/ slow motion with timer/stroboscope with scale. Bs 2 Longer hacksaw blade/heavier mass (to increase time of oscillation)/more oscillations than already used (larger n). Cp Judging beginning/end of oscillation/complete oscillation. Cs Motion/position sensor placed at side of mass/fiducial marker/(stationary) reference marker and stated purpose. Dp Length error e.g. parallax error in reading the ruler/difficulty in establishing centre of mass/ ends of blocks. Ds Find the mid-point of the mass by finding the distance to both ends and taking an average/ thinner rule with reason/scale starts at 0 cm with reason/scale on blade/corrections for parallax error. Ep Difficulty in setting up the apparatus horizontally/difficulty in assembly with detail. Es Use spirit level/measure up from bench/ partner to help with set up. [Total: 20]