Cambridge A Level Physics 9702 — 2005 May/June Paper 3 · Variant 1

This document consists of 6 printed pages and 2 blank pages. SPA (MML 8097 3/04) S84954/2 © UCLES 2005 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level PHYSICS 9702/03 Paper 3 Practical Test May/June 2005 1 hour 15 minutes Candidates answer on the Question Paper. Additional Materials: As specified in the Confidential Instructions. 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 in the spaces provided on the Question Paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer the one 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. Marks are mainly given for a clear record of the observations actually made, for their suitability and accuracy, and for the use made of them. 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. Centre Number Candidate Number Name If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the space given at the top of this page. Stick your personal label here, if provided. For Examiner’s Use

1 In this question you will investigate how the force required to maintain equilibrium of a suspended mass depends on the angle between the line of action of the force and the horizontal. You are supplied with a piece of string that has a loop at each end and one in the middle. (a) (i) Suspend the mass from the middle loop and attach the other loops to a mounted boss and a newton-meter as shown in Fig. 1.1. The body of the newton-meter must be clamped so that it is along the line of action of force F. You may need to rotate the clamp in order to achieve this. The section AB of the string should be horizontal and the bases of the stands should be clamped to the bench. Fig. 1.1 A newton-meter stand B F 2 9702/03/M/J/05 © UCLES 2005 For Examiner’s Use

(ii) Using the protractor, measure the angle
. Record the value of
and the reading F from the newton-meter.
= … F = … (iii) Determine the percentage uncertainty in the value of
. percentage uncertainty in
= … (b) State two difficulties that you had when making measurements of F and
. 1 … … 2 … … 3 [Turn over 9702/03/M/J/05 © UCLES 2005 For Examiner’s Use

(c) Change the height of one of the bosses above the bench and adjust the separation of the stands to give new values of
and F. The section AB must remain horizontal. You will need to loosen a G-clamp in order move a stand. Measure and record the new values of
and F. Repeat the procedure until you have six sets of readings for
and F. You must ensure that, when you are taking readings, the body of the newton-meter is along the line of action of the force F and that it does not go off scale. Include all six sets of values of F,
and 1/sin
in your table of results. (d) Plot a graph of F (y-axis) against 1/sin
(x-axis) and draw the best straight line through the points. (e) Determine the gradient and y-intercept of the line. gradient = … y-intercept = … 4 9702/03/M/J/05 © UCLES 2005 For Examiner’s Use

5 [Turn over 9702/03/M/J/05 © UCLES 2005 For Examiner’s Use

(f) The equation that relates F and
is mg F = ––––– + k sin
where m is the mass of the load, k is a constant and g is the acceleration of free fall. You may take the value of g to be 9.81 m s–2. Use your answers from (e) to determine values for m and k. Include appropriate units. m = … k = … 6 9702/03/M/J/05 © UCLES 2005 For Examiner’s Use

BLANK PAGE 8 9702/03/M/J/05 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 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 and Advanced Level MARK SCHEME for the June 2005 question paper 9702 PHYSICS 9702/03 Paper 3 (Practical Test), maximum raw mark 25 This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. This shows the basis on which Examiners were initially instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination. 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 discussion or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the June 2005 question papers for most IGCSE and GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Grade thresholds for Syllabus 9702 (Physics) in the June 2005 examination. minimum mark required for grade: maximum mark available A B E Component 3 25 22 20 15 The thresholds (minimum marks) for Grades C and D are normally set by dividing the mark range between the B and the E thresholds into three. For example, if the difference between the B and the E threshold is 24 marks, the C threshold is set 8 marks below the B threshold and the D threshold is set another 8 marks down. If dividing the interval by three results in a fraction of a mark, then the threshold is normally rounded down.

June 2005 GCE A AND AS LEVEL MARK SCHEME MAXIMUM MARK: 25 SYLLABUS/COMPONENT: 9702/03 PHYSICS Paper 3 (Practical Test)

Page 1 Mark Scheme Syllabus Paper A and AS LEVEL - JUNE 2005 9702 3 © University of Cambridge International Examinations 2005 (a) (iii) Absolute uncertainty = 10 - 50, one mark. Can be credited from (a) (ii). [2] Percentage uncertainty in first value of θ (i.e. ratio correct and x 100), one mark. A bald answer with no working scores zero. Check value if absolute uncertainty given but no ratio. Allow half range/av. value x 100. (b) Two difficulties: one mark each [2] Examples of creditworthy answers are as follows:
Indicator on the newton-meter sticks
Difficultly of too much compressive force to body of newton-meter when clamping
Difficult to position centre of protractor on knot
Protractor ‘wobbles’ when being held by hand/‘wobbly hands’
Parallax error when reading the scale on the protractor/newton-meter
Hard to align newton-meter parallel to line of action of F
Difficulty of ensuring AB is horizontal
Difficulty with zero on scale of newton-meter
Thick string makes measurement of angle hard
The centre of the knot could not be accurately located
‘The air-conditioning makes the string move’/reason for moving string Candidate’s answers must relate to this experiment, and the measurement of F and θ . Examples of vague answers which are not acceptable are as follows:
‘The string was moving’ or ‘the mass was oscillating’
‘I did not have any difficulties’
‘The clamp is loose, so I tightened it’
It was difficult to read the scale on the newton-meter/angle
Unqualified ‘adjusting the retort stand’
The mass is not in equilibrium
Unqualified ‘parallax error’ (c) Readings [5] 6 sets of readings scores three marks; 5 sets, two marks; 4 sets, one mark. Check a value for 1/sin θ . Tick if correct and score one mark. Ignore small rounding errors. Ignore POT errors in F. If incorrect, write in correct value and do not award the mark. All values of θ must lie between 900 and 1800; one mark. Help given by Supervisor, then -1. Excessive help then -2. Quality of results [2] Judge by scatter of points about the line of best fit. 6 trend points with little scatter scores two marks. 6 trend points with ‘a fair amount of scatter’ scores one mark. 5 trend points with little scatter scores one mark. Shallow curve scores one mark. 4 trend points (or less) scores zero. Considerable scatter scores zero. Wrong trend scores zero. If wrong angle measured (i.e. values of θ
< 900) then cannot judge quality. Score zero.

Page 2 Mark Scheme Syllabus Paper A and AS LEVEL - JUNE 2005 9702 3 © University of Cambridge International Examinations 2005 Column headings [1] Apply to F only. There must be some distinguishing feature between F and N. Accept F/N, F (N), F in N, N F . Allow the unit to be written in words. Do not allow F, N. Do not allow F/n. Consistency [2] Apply to F and θ only. One mark each. All the values of F should be given to one decimal place. Do not accept 0.1 g if spring balance used. Values of θ must be given to the nearest degree. (d) Axes [1] Scales must be such that the plotted points occupy at least half the graph grid in both the x and y directions (i.e. at least 6 squares in the y-direction and 4 squares in the x-direction). Scales must be labelled with the quantity plotted. Ignore units. Do not allow awkward scales (e.g. 3:10, 6:10, 8:10 etc.) Do not allow more than three large squares without a scale marking. Plotting of points [1] Count the number of plots on the grid and write this value by the line. Do not allow plots in the margin area. Check a suspect plot. The number of plots must correspond to the number of observations. Score zero if the number of plots is less than the number of observations. Circle and tick if correct. If incorrect, show correct position with arrow, and do not award the mark. Work to half a small square. Line of best fit [1] Expect to see a reasonable balance of points about the line of best fit. Five trend plots are needed for this mark to be awarded. There must be a straight line drawn through a linear trend of points. (e) Determination of gradient [2] ∆used must be greater than half the length of the drawn line; one mark Read-offs and ratio correct (i.e. check that dy/dx has been found and not dx/dy); one mark. Ignore any unit given with the value. y-intercept [1] The value may be read directly or calculated using y = mx + c and a point on the line. If a point on the line has been used, check that there is a valid substitution into y = mx + c. Do not look at final numerical answer if the method of working is correct. Tick the zero on the x-axis if present, or write FO if not.

Page 3 Mark Scheme Syllabus Paper A and AS LEVEL - JUNE 2005 9702 3 © University of Cambridge International Examinations 2005 (f) Gradient equated with mg [1] If axes reversed on graph then do not award this mark. Value of m [1] Working must be correct (i.e. gradient/g). Allow ecf from incorrect gradient. Intercept equated with k [1] Value must agree with y-intercept on page 4. Significant figures in m and k. Accept 2 or 3 sf only. [1] Units of m and k correct [1] m can be in kg or g (consistent with working). k must be in N. Note: a substitution method in (f) can only score SF and unit marks. [25 marks in total for this question]