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GCE Physics A - · PDF fileCONTENTS Advanced GCE Physics A (H558) Advanced Subsidiary GCE Physics (H158) OCR REPORT TO CENTRES Content Page G481 Mechanics 4

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  • Oxford Cambridge and RSA Examinations

    GCE

    Physics A

    Advanced GCE H558

    Advanced Subsidiary GCE H158

    OCR Report to Centres June 2016

  • OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range of qualifications to meet the needs of candidates of all ages and abilities. OCR qualifications include AS/A Levels, Diplomas, GCSEs, Cambridge Nationals, Cambridge Technicals, Functional Skills, Key Skills, Entry Level qualifications, NVQs and vocational qualifications in areas such as IT, business, languages, teaching/training, administration and secretarial skills. It is also responsible for developing new specifications to meet national requirements and the needs of students and teachers. OCR is a not-for-profit organisation; any surplus made is invested back into the establishment to help towards the development of qualifications and support, which keep pace with the changing needs of todays society. This report on the examination provides information on the performance of candidates which it is hoped will be useful to teachers in their preparation of candidates for future examinations. It is intended to be constructive and informative and to promote better understanding of the specification content, of the operation of the scheme of assessment and of the application of assessment criteria. Reports should be read in conjunction with the published question papers and mark schemes for the examination. OCR will not enter into any discussion or correspondence in connection with this report. OCR 2016

  • CONTENTS

    Advanced GCE Physics A (H558)

    Advanced Subsidiary GCE Physics (H158)

    OCR REPORT TO CENTRES

    Content Page

    G481 Mechanics 4

    G482 Electrons, Waves and Photons 9

    G483 Practical Skills in Physics 1 12

    G484 The Newtonian World 17

    G485 Fields, Particles and Frontiers of Physics 21

    G486/02: Practical Skills in Physics 2 27

  • OCR Report to Centres - June 2016

    4

    G481 Mechanics

    General Comments: The marks for this paper ranged from 6 to 60 and the mean mark was about 40. Most candidates used their time sensibly; there was little evidence of candidates running out of time. There were no significant omissions of specific questions. The paper was taken in the final year of the teaching of this course. This resulted in many candidates being at the end of the two year course and this was reflected in the high standard of many of the candidates' responses. Many Centres have continued to make good use of past papers, mark schemes and Examiners' reports. Most candidates showed good analytical skills and a decent command of technical language. Some descriptive responses lacked structure and knowledge of basic physics. Very few candidates took advantage of expressing their ideas in the form of bullet points. On some scripts, potentially good answers were marred by premature rounding of numbers and erroneous transfer of data between questions. Generally, candidates made good use of their calculators and often wrote the final answers in scientific notation. Few numerical answers were left as fractions or as surds. It is important that the final numerical answer conveys the significant figures used in the question and very few candidates made mistakes in their use of significant figures or made rounding errors. There were some very good scripts with clearly laid out physics and well presented calculations; such scripts reflect well on the candidates. The comments that follow tend to relate mainly to the opportunities that were missed by the candidates. Comments on Individual Questions: Question No. 1(a) Candidates answered this opening question well with the vast majority writing a succinct

    and correct definition. A noticeable incorrect answer was 'the rate of change of velocity per unit time'; candidates need to be aware that in dynamics the term 'rate' includes per unit time.

    1(b) This was another well answered question with almost all candidates scoring the mark.

    The commonest error was to write words to the effect that 'velocity is a vector and as acceleration contains velocity, it too, must be a vector'.

    1(c)(i)1 Candidates had difficulty with this question. Many knew the motion of the object was not

    uniform acceleration and wrote 'non-uniform acceleration', which was insufficient for the mark. Many included the word rate in their answer in such a way that they negated a possibly correct answer. The correct way to have used rate to score the mark would be to write 'increasing rate of change of velocity', which a few candidates did.

    1(c)(ii)2 Twice as many candidates answered this part of Q1(c) correctly. Again, incorrect

    inclusion of the word rate penalised some candidates.

  • OCR Report to Centres - June 2016

    5

    1(c)(ii) It was well understood that the area beneath a velocity time graph gives distance. A small number of candidates tried to answer this question with reference to gradients or the length of the base line - but omitted to mention area. A few candidates used incompatible adjectives such as 'it has a shorter area'.

    1(d) Many candidates achieved both marks on this question. Two common errors were to

    use time = distance divided by velocity as if the blood were not accelerating or to make a transcription error by using 0.20 instead of 0.02.

    2(a) Over 85% of candidates wrote correct answers. A small number got Aristotle and

    Galileo's names interchanged. One common error was to write that Aristotle said acceleration depended on mass, without specifying that according to Aristotle heavier would mean faster.

    2(b)(i) Many correct answers here also. One common error was to state that mass or weight

    would have an effect on aerodynamic drag. 2(b)(ii) Marks were lost here for writing 9.81 without the unit or using an incorrect unit.

    Candidates also incorrectly wrote that the drag was small or minimal rather than zero. Some wrote that 'the only force acting was gravity'; the mark was awarded for 'the only force acting is weight'. Many candidates wasted time writing about what happened to the acceleration as time passed - this was not asked for.

    2(b)(iii) A majority of candidates scored both marks. Where marks were lost, it was for drawing

    a line showing increasing acceleration or drawing a straight line for the first 10 s. A

    tolerance of 1 s was allowed in the line becoming zero after 10 s. 2(b)(iv) Candidates found this to be a more straightforward question to answer and wrote full

    and correct answers. A small number calculated the net force as 240 N and stopped there.

    3(a) All the candidates knew which formula to use but some used the incorrect height.

    Others arrived at the correct answer but wasted time calculating the change in gravitational potential energy (GPE) over 34.5 m, then subtracting the change in GPE over 9.5 m.

    3(b) Almost universally correct answers. 3(c) A more testing question. Candidates attempted to use arguments about the motorcycle

    accelerating but failed to mention energy or work so didn't score the mark. Many candidates explained the difference in energy by discussing heat losses - which would have resulted in less kinetic energy rather than more. This question discriminated well between the upper, mid and lower quartiles.

    3(d) Another excellent discriminating question. Many candidates wrongly applied equations

    of motion to the situation, using the length of the ramp as displacement in an attempt to determine the acceleration and hence the force, resulting in answers around 712 N.

    3(e)(i) A significant number of candidates used 30 m s-1 as the initial velocity leading to an

    incorrect answer. Candidates who did not rearrange the formula to make t the subject of the equation did not score the second mark.

    3(e)(ii) There were many good answers but a number of candidates who had failed to

    determine 1.39 s in the previous question omitted this question.

  • OCR Report to Centres - June 2016

    6

    4(a) The most common mistake was to state that the resultant force was 900 N. This is the vertical reaction force. Candidates that considered horizontal and vertical forces separately usually described a zero horizontal resultant but a non-zero vertical resultant. Stating 'the velocity is constant' was insufficient for the second mark as this was given in the stem of the question.

    4(b) Candidates were expected to include and to correctly spell the word perpendicular;

    most did score this mark. A common mistake was to fail to mention the pivot / point. A small number wrote the law of moments or the definition of work done by a force.

    4(c) The most common error was to write a statement such as 'to be a couple forces must

    act in opposite directions', without saying that in this case the two forces acted in the same direction. Writing 'both forces act upwards' was insufficient, as it could be that two forces acting downwards would have constituted a couple.

    4(d) The candidates demonstrated a good understanding of moments with almost 90% of

    candidates answering this question correctly. A small number did various calculations with the distances given on the diagram; this was unnecessary and lead to incorrect answers.

    4(e) Whilst the majority of the candidates knew that the force at X decreased, many were

    unable to explain why clearly. Many wrote statements like 'because the distance to the pivot increases' without stating what distance or which pivot. Candidates needed to specify points using the labels given on the diagram.

    5(a)(i) This ma