GCE AS and A Level. Physics A. AS exams 2009 onwards A2 exams 2010 onwards. Unit 4: Approved specimen mark scheme. Version 1.2

Transcription

1 GE AS and A Level Physics A AS exams 009 onwards A exams 010 onwards Unit : Approved specimen mark scheme Version 1.

2 version : 1. abc General ertificate of Education Physics 51 Specification A PHYA Fields and Further Mechanics Mark Scheme

3 The specimen assessment materials are provided to give centres a reasonable idea of the general shape and character of theplanned question papers and mark schemes in advance of the first operational exams. Mark schemes are prepared by the Principal Examiner and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation meeting attended by all examiners and is the scheme which was used by them in this examination. The standardisation meeting ensures that the mark scheme covers the candidates responses to questions and that every examiner understands and applies it in the same correct way. As preparation for the standardisation meeting each examiner analyses a number of candidates scripts: alternative answers not already covered by the mark scheme are discussed at the meeting and legislated for. If, after this meeting, examiners encounter unusual answers which have not been discussed at the meeting they are required to refer these to the Principal Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of candidates reactions to a particular paper. Assumptions about future mark schemes on the basis of one year s document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper. Further copies of this Mark Scheme are available to download from the AQA Website: opyright 009 AQA and its licensors. All rights reserved. OPYRIGHT AQA retains the copyright on all its publications. However, registered centres for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to centres to photocopy any material that is acknowledged to a third party even for internal use within the centre. Set and published by the Assessment and Qualifications Alliance. The Assessment and Qualifications Alliance (AQA) is a company limited by guarantee registered in England and Wales (company number 67) and a registered charity (registered charity number 107). Registered address: AQA, evas Street, Manchester M15 6EX r Michael resswell irector General

4 PHYA: Fields and Further Mechanics Keys to Objective Test Questions 1 A A 8 9 A A A Question 1 kinetic energy is not conserved! (or velocity of approach equals velocity of separation) 1 (b) (use of p = mv gives) p = ! =.7 kg m s -1! (use of F = Δ ( mv) Δt.7 gives) F = = 180 N!! [or a = v u t = = 00 (m s -1 )]! F = ma = = 180 N! Total 5 Question mg = ke! k = 0 10 = 61(.) N m -1! T = m = π = π k ! (= s) f 1 = T = ! (= 1.5(0) Hz)

5 (b) The marking scheme for this part of the question includes an overall assessment for the Quality of Written ommunication (QW). There are no discrete marks for the assessment of QW but the candidates QW in this answer will be one of the criteria used to assign a level and award the marks for this part of the question. Level Good Modest Limited 1 escriptor an answer will be expected to meet most of the criteria in the level descriptor - answer supported by an appropriate range of relevant points good use of information or ideas about physics, going beyond those - given in the question - argument well structured with minimal repetition or irrelevant points accurate and clear expression of ideas with only minor errors of spelling - punctuation and grammar - answer partially supported by relevant points good use of information or idea about physics given in the question but - limited beyond this - the argument shows some attempt at structure the ideas are expressed with reasonable clarity but with a few errors of - spelling, punctuation and grammar - valid points but not clearly linked to an argument structure - limited use of information or ideas about physics - unstructured - errors in spelling, punctuation and grammar or lack of fluency Mark range incorrect, inappropriate or no response 0 examples of the sort of information or idea that might be used to support an argument forced vibrations (at 0. Hz)! amplitude fairly large ( 0 mm)! in phase with driver! resonance (at 1.5 Hz)! amplitude very large (> 0 mm)! oscillations may appear violent! phase difference at 90º! (iii) forced vibrations (at 10 Hz)! small amplitude! out of phase with driver or phase lag of π on driver! Total 10

6 Question period is hours (or equal to period of Earth s rotation)! remains in fixed position relative to surface of Earth! equatorial orbit! max (b) same angular speed as Earth (or equatorial surface)! GMm = mω r! r π T = ω! r GMT = π = ( π 600) 1/! (gives r =. 10 km) 6 ΔV = GM 1 1 R r! = = (J kg -1 )! (c) ΔE P = mδv (= ) = J! (allow ecf for value of ΔV) signal would be too weak at large distance! (or large aerial needed to detect/transmit signal, or any other acceptable reason) the signal spreads out more the further it travels! for road pricing would reduce congestion stolen vehicles can be tracked and recovered uninsured/unlicensed vehicles can be apprehended against road pricing would increase cost of motoring possibility of state surveillance/invasion of privacy!! any valid points (must be for both for or against) Total 1

7 Question T cos 6º = mg! T sin 6º = F! hence F = mg tan 6º! [or by use of triangle: sides correct! 6º correct! tan 6º = F/mg!] (b) V 00 (use of E = gives) E = d = V m -1! F mg tan 6 (use of Q = gives) Q E E = tan ! = ! (allow ecf for value of E from ) Total 6 Question 5 E (= ½ V = ) = 0.90 J! W (= QV = V = ) = 1.8 J! (b) (V = V 0 e -t/r ) gives 0 = 100 e -t/r! t = (-R ln (0/100) = s) = s! image would be less sharp (or blurred) because the discharge would last longer and the image would be photographed as it is moving! image would be brighter because the capacitor stores more energy and therefore produces more light! Total 6

8 Question 6 greater flux (linkage) or more flux lines (at same distance) [or stronger magnet produces flux lines closer together]! greater rate of change of flux (linkage) [or more flux lines cut per unit time]! induced emf [or =] rate of change of flux (linkage)! [or using = NA Δ! Δ is larger since magnet is stronger! Δt N, A and Δt are the same at the same speed is larger!] (b) area swept out ΔA = lvδt! (c) ΔФ (= ΔA) = lvδt! ΔΦ = ( N) = Δt lvδt Δt gives result! ω (= πf) = π 16! = 101 rad s -1! v (= rω) = =.() m s -1! (iii) (allow ecf for value of ω from ) (= lv) = ! = 5.7(9) 10 - V! (allow ecf for value of v from ) [or accept solutions using = fπr to give 5.7(9) 10 - V] 5 Total 11

9 Assessment Objectives Section A 1 AO1 AO AO AO1 5 AO 6 AO 7 AO1 8 AO 9 AO 10 AO1 11 AO 1 AO1 1 AO 1 AO 15 AO 16 AO1 17 AO1 18 AO 19 AO 0 AO 1 AO1 AO AO1 AO 5 AO Total 5 Summary Marks Ability tested % 9 AO1 Knowledge and Understanding 6 15 AO Application 60 1 AO How Science Works Assessment Objectives Section Question No Ability tested Marks 1 AO1 1 (b) AO1/AO Question Total 5 AO (b) AO1 6 Question Total 10 AO1 (b) AO 6 (c) AO1/AO Question Total 1 AO (b) AO1/AO Question Total 6 5 AO (b) AO1 1 (c) AO Question Total 6

10 6 AO1 (b) AO (c) AO 5 Question Total 11 Total 50 Summary Marks Ability tested % 17 AO1 Knowledge and Understanding 1 AO Application 6 AO How Science Works Summary Total Unit Marks Ability tested % 6 AO1 Knowledge and Understanding 5 6 AO Application 61 AO How Science Works