Cambridge A Level Physics 9702 — 2008 May/June Paper 3 · Variant 2

This document consists of 8 printed pages and 4 blank pages. SPA (FF/DT) T46316/6 © UCLES 2008 [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 all 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 2 5 2 1 8 8 6 8 6 * PHYSICS 9702/32 Paper 32 Advanced Practical Skills 2 May/June 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/M/J/08 [Turn over For Examiner’s Use © UCLES 2008 You may not need to use all of the materials provided. 1 In this experiment you will measure the period of oscillation of a wooden rod weighted at different positions. You will use the results to determine the mass of the rod. (a) Set up the rod so that it is pivoted by a nail as shown in Fig. 1.1. Another nail should be placed through the bottom hole and a 0.100 kg mass is to be held in place with a small piece of Blu-Tack. nail cork nail 0.100 kg mass Fig. 1.1 (b) Measure the distance l between the two nails. l = … m (c) Displace the rod so that it oscillates with a small amplitude in a vertical plane as shown in Fig. 1.2. Fig. 1.2 Determine the period T of oscillation. T = … s

4 9702/32/M/J/08 For Examiner’s Use © UCLES 2008 (d) Move the bottom nail and the mass to different holes and repeat (b) and (c) until you have six sets of readings for l and T. Include values for T 2 in your table of results. (e) Plot a graph of T 2 on the y-axis against l on the x-axis and draw the line of best fit. (f) Determine the gradient and y-intercept of this line. gradient = … y-intercept = …

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

6 9702/32/M/J/08 For Examiner’s Use © UCLES 2008 (g) It is suggested that the relationship between T 2 and l is T 2 = 4π2ml g (m + M ) + z where m is 0.100 kg, M is the mass of the rod, g = 9.81 N kg –1 and z is a constant for this experiment. Use your answers from (f) to determine the values of M and z. Give appropriate units. M = … z = …

9702/32/M/J/08 [Turn over BLANK PAGE Please turn over for Question 2 7

8 9702/32/M/J/08 For Examiner’s Use © UCLES 2008 You may not need to use all of the materials provided. 2 (a) Roll out the modelling clay into a cylinder of length 4 cm. Wrap the 4 cm width of paper around the cylinder’s length and fix with Sellotape as shown in Fig. 2.1. card modelling clay Sellotape 4 cm Fig. 2.1 (b) (i) Use the string to measure the circumference c of the cylinder. c = … (ii) Estimate the percentage uncertainty in c. % uncertainty in c = … (iii) Use your answer to (i) to determine the radius r of the cylinder. r = …

9 9702/32/M/J/08 For Examiner’s Use © UCLES 2008 (c) Place the cylinder at the top of the slope and release it so that it rolls down the slope. Measure the time t for the cylinder to travel a distance of 50 cm from rest. t = … s (d) Undo the paper and roll the modelling clay into a cylinder of length 8 cm. Wrap the 8 cm width of paper around the cylinder’s length and fix with Sellotape. Repeat (b)(i), (b)(iii) and (c). c = … r = … t = … (e) Explain whether your results support the idea that t 2 is proportional to r. … … … … … [Turn over

10 9702/32/M/J/08 For Examiner’s Use © UCLES 2008 (f) (i) State four sources of error or limitations of the procedure for 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/M/J/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 May/June 2008 question paper 9702 PHYSICS 9702/32 Paper 32 (Advanced Practical Skills 2), 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. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. 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 May/June 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 – May/June 2008 9702 32 © UCLES 2008 1 Manipulation, measurement and observation Successful collection of data (b) Value of length 0.470m to 0.490m (to nearest cm or mm). [1] (c) 10T (or more) has been measured (could be evidence in table of results). [1] (c) Repeat readings. At least two readings of 10T or T (could be in table). [1] (d) Results Write the number of readings as a ringed total next to the table of results. Six sets of values for T and l scores 3 marks, five sets scores 2 marks. If raw data shows reverse trend then –1. [3] (d) Apparatus set up without help from Supervisor. [1] Range and distribution of values (d) Range of results (including the value in (b)). Must include 48cm and 18cm (nominal values), with no interval greater than 7cm. [1] Presentation of data and observations Table: layout (d) Column headings. Each column heading must contain a quantity and a unit where appropriate. Ignore units in the body of the table. There must be some distinguishing mark between the quantity and the unit (solidus is expected, but accept, for example, T (s)). [1] Table: raw data (d) Consistency of presentation of raw readings. All values of 10T (or T) must be given to the same number of decimal places. If these are to the nearest second then –1. Allow trailing zeros. [1] Table: calculated quantities (d) Significant figures. Apply toT ². Take trailing zeros into account. If 10T is given to 2 sf, then accept T ² to 2 or 3 sf. If 10T is given to 3 sf, then accept T ² to 3 or 4 sf. If 10T is given to 4 sf, then accept T ² to 4 or 5 sf. [1] (d) Values of T ² correct. Check a value (from candidate’s T). If incorrect, write in the correct value. [1]

Page 3 Mark Scheme Syllabus Paper GCE A/AS LEVEL – May/June 2008 9702 32 © UCLES 2008 Graph: layout (Graph) Axes. Sensible scales must be used (not 3:10 etc.), with labels at least every three large squares. Scales must be such that the plotted points occupy at least half the graph grid in both x and y directions. Scales must be labelled with the quantity which is being plotted. Ignore units. Indicate false origin with FO. Allow reversed axes, but if wrong graph plotted then –1. [1] Graph: plotting of points (Graph) All observations must be plotted. Count and circle the number of plots. Ring and check a suspect plot. Tick if correct. Re-plot if incorrect. Work to an accuracy of half a small square. Don’t allow blobs (i.e. large dots with diameter ≥ half a small square). [1] Graph: trend line (Graph) Line of best fit. Allow 5 trend plots. Judge by scatter of points about the candidate's line. Indicate best line if candidate's line is not the best line. Don’t allow a line thicker than half a small square. [1] Quality of data (Graph) Judge by scatter of points. Allow 2cm (scaled) in the l direction either side of any line that could be drawn. All plots from table are needed for this mark to be scored. Do not award this mark if the trend is wrong or if wrong graph is drawn. [1] Analysis, conclusions and evaluation Interpretation of graph (f) Gradient. The hypotenuse of the ∆ must be ≥ half the length of the drawn line. Read-offs must be accurate to half a small square. Check for ∆y/∆x (do not allow ∆x/∆y). [1] (f) The y-intercept value must be read to the nearest half square. Check for false origin. The value can be calculated using ratios or y = mx + c. [1] Drawing conclusions (g) Value for M. Check substitution into “gradient = 4π2m/g(m+M)” is correct. Allow 10 – 70g. Unit required. [1] (g) Value for z. Must equal the y-intercept. Unit required (s2). 2 or 3 s.f. [1] [Total: 20]

Page 4 Mark Scheme Syllabus Paper GCE A/AS LEVEL – May/June 2008 9702 32 © UCLES 2008 2 Manipulation, measurement and observation Successful collection of data (b) (i) First measurement of circumference to nearest mm. Unit must be given. [1] (c) Measurement of t1. [1] (c) Repeated measurements for t1 (or t2). [1] (d) Second measurement of c. [1] (d) Second measurement of circumference < first measurement. [1] (d) Measurement of t2. [1] Quality of data (d) t decreases when c decreases. [1] Presentation of data and observations Display of calculation and reasoning (b) (iii) Value of first radius calculated correctly. Consistent unit must be given. Check correct use of c = 2πr. [1] (d) Value of second radius, with same s.f. (or one more than) c2. [1] (e) Correct calculation to check proportionality. Possibilities include: two calculations of t2/r or ratio of t2 values and ratio of r values both calculated. [1] Analysis, conclusions and evaluation Drawing conclusions (e) Sensible comments relating to calculations and suggested relationship. The only way this mark can be scored without the first (e) mark is if the results show the wrong trend and it is argued that this disproves the suggested relationship (but don’t credit ‘results show inverse proportionality’). [1]

Page 5 Mark Scheme Syllabus Paper GCE A/AS LEVEL – May/June 2008 9702 32 © UCLES 2008 Estimating uncertainties (b) (ii) Percentage uncertainty in c. ∆c must be 0.2–0.5cm (or half the range if repeated readings). Correct ratio idea required (∆c/circumference) × 100%. [1] Identifying limitations (f) (i) Underline and tick relevant point (one from each section): A - two sets of readings are not enough (to draw a conclusion) B - difficult to make accurate cylinder shape - cylinder radius/circumference varies C - cylinder doesn’t roll straight D - human reaction error (in timing) - measured time is very short not ‘difficult to release cylinder and start stopwatch together’ E - difficult to judge end point [4 max] Suggesting improvements (f) (ii) Underline and tick relevant point (one from each section): A - test many cylinders and plot a graph - test many cylinders and find many values of k B - method of making more accurate cylinder D - time over longer distance - use shallower angle ramp - use light gates/pressure switches to measure time - use freeze-frame photography to measure time - use motion sensor to measure time not just ‘use video’ not ‘repeated readings’ not just ‘use computer/data logger’ E - mark distance with lines on ramp (to eliminate parallax) not ‘use a pointer’ X - new method (e.g. vernier calipers) to measure average diameter [4 max] [Total: 20]