9702_w10_er

Please download to get full document.

View again

of 59
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Information Report
Category:

Creative Writing

Published:

Views: 8 | Pages: 59

Extension: PDF | Download: 0

Share
Related documents
Description
Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers PHYSICS Paper 9702/11 Multiple…
Transcript
Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers PHYSICS Paper 9702/11 Multiple Choice Question Question Key Key Number Number 1 D 21 A 2 C 22 B 3 B 23 A 4 A 24 C 5 B 25 A 6 C 26 A 7 B 27 D 8 A 28 A 9 C 29 D 10 B 30 B 11 B 31 C 12 B 32 A 13 A 33 B 14 B 34 C 15 D 35 C 16 B 36 B 17 D 37 A 18 D 38 C 19 D 39 D 20 D 40 C In this paper only 2 questions had more than 70% correct answers. These were Questions 35 and 38. There did not appear to be any falling off of achievement with Questions 31 to 40 so there was no indication of candidates running out of time. Comments on Specific Questions Questions 1 to 6 were answered reasonably well. Question 7 This question had 47% correct answers though many candidates did not realise that the horizontal velocity of the ball will also be affected by air resistance. It cannot stay constant over a considerable time but will fall to zero, while the vertical velocity will rise to a constant value. The question states that the ball is affected by air resistance; this cannot be just its vertical motion. 1 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers Question 13 Only 28% of candidates answered correctly by performing the calculation, (15 × 3) – (10 × 2) – (5 × 2) = 15 N m. Many candidates must have assumed that the horizontal force provided a clockwise moment and others must have guessed an answer. Question 15 40% of candidates chose either B or C; diagrams that do not show a resultant force of zero. Another 40% did get the correct answer, D. Question 16 There seemed to be a good deal of guessing in answering this question, suggesting that candidates may benefit from further support in the subject of thermal physics. Question 18 Only 23% of candidates could write “m1gv = m2gv + answer”. The kinetic energy distractor here ignores completely any energy input. Question 24 This question produced some unnecessarily poor answers. This type of question is very easy to answer correctly by one simple piece of advice – namely “draw the new wave on the paper as it will appear a short time later”. Candidates are often very reluctant to use the paper itself to write on. With the additional line on the diagram it becomes clear that the correct answer is C. At A the water must be moving downwards – yet 60% of candidates put this as their answer and only 9% gave the correct answer. Question 25 Candidates often correctly found the factor of 0.5 but forgot to square it for the intensity. Question 27 Many candidates showed that they are not familiar with the wavelengths of the constituents of the electromagnetic spectrum. Question 33 Questions such as this ought to be regarded as routine, but candidates still need to work through them carefully. Now that space is being left for working it is essential that candidates use it. For their own benefit they should use words when working things out and not just a string of letters and figures. It is all too easy to make careless mistakes when answers are worked out in one’s head. Question 37 The voltmeter must read 4 V when the slider is at X. When it moves to Y, potentiometer P and the voltmeter are in series with almost all the resistance in the voltmeter, and hence the p.d. across the voltmeter is still 4 V. Only 26% of candidates realised this. About 60% of the candidates thought that B or C was the correct answer. Question 38 This was well answered with 79% getting the correct answer. 2 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers PHYSICS Paper 9702/12 Multiple Choice Question Question Key Key Number Number 1 A 21 A 2 B 22 A 3 A 23 C 4 C 24 C 5 D 25 D 6 D 26 C 7 D 27 B 8 A 28 A 9 C 29 A 10 B 30 D 11 B 31 A 12 C 32 C 13 D 33 D 14 D 34 B 15 D 35 B 16 B 36 B 17 C 37 B 18 C 38 D 19 C 39 C 20 D 40 B Only one question produced more than 90% correct responses but there were several questions where the percentage of correct responses was rather low. Details of these questions will follow in this report. The time allocation for this paper is very short so any checking of answers needs to be done immediately after obtaining the initial response. It is hoped that by leaving plenty of space for working, candidates would be encouraged to construct their answers in writing rather than by working in their heads. Questions 30 to 40 were answered as well as other sections of the paper so there was no indication of candidates running out of time. Comments on Specific Questions Question 4 This question produced only 53% correct answers. Significant figures are a perpetual problem, especially when zeros are involved, but here three significant figures are clearly necessary. 3 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers Question 5 This also resulted in a low proportion correct of 39%. Candidates need to know that with subtraction of data the uncertainty is still added, as arithmetic will show by obtaining highest and lowest possible values for x. Question 7 This was the first of the questions with an unduly low percentage of correct responses with only 16% correct. Candidates should have been able to eliminate A and B just from the first line of the question. “Positive is upwards”: the acceleration due to gravity is therefore negative. At the ceiling the downward acceleration is even larger so D is correct. Question 8 This was a complex question and it was difficult to find any short cut to the answer. The best way of doing the calculation is to consider the first stage and then both stages together. Then the initial velocity can easily be eliminated. Question 9 This question ought to have taken a very brief time to answer correctly. A cannot be correct because the particle is still going in the initial direction. In B it stops and in D it must have undergone an elastic (not an inelastic) collision. C, the correct answer was chosen by only 11% of candidates. Question 13 59% of candidates incorrectly gave B as the answer. The reading of course is not the upthrust but the weight minus the upthrust. The weight is unchanged so D is correct, but only 13% gave this as their answer. Question 22 Only 23% were able to reach the correct conclusion in this question, perhaps because they assumed that a high spring constant is what is required for large deflection. Here the thinner spring stretches most when the loading is light but it can go no further than the rigid box. The sensitivity falls thereafter. A circular scale on a commercial balance with a similar difference of sensitivity will perhaps have a scale occupying 10 cm for the first 100 g, followed by 40 cm for a total mass of 4 kg. Question 28 This question had only 32% correct responses, largely because candidates did not appreciate that with an electric field the horizontal velocity remains unchanged but that there will be an increase in speed because of the vertical component of velocity given to the electron. Questions 31 A large number (40%) thought that electrons were stationary in a wire carrying no current, rather than moving at random. Question 32 Only 23% realised that it is the work done across the internal resistance that causes the drop in p.d. Question 34 Many candidates thought that D was the correct response. A bit of extra thought was necessary to see that the answer is B. Question 40 The last question caused some difficulty. The half-life is uncertain because of randomness of the decay, but A is wrong in any case because the time interval between the 424 and 212 readings is 80 minutes and not 90 minutes. 4 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers PHYSICS Paper 9702/13 Multiple Choice Question Question Key Key Number Number 1 B 21 B 2 B 22 D 3 C 23 A 4 D 24 A 5 A 25 C 6 A 26 D 7 C 27 A 8 B 28 D 9 B 29 B 10 B 30 A 11 B 31 C 12 C 32 C 13 D 33 C 14 A 34 B 15 B 35 A 16 D 36 A 17 D 37 B 18 B 38 C 19 A 39 C 20 D 40 D The overall standard of the candidates was very encouraging but only 3 questions had 90% or more correct answers. These were Questions 7, 33 and 39. Questions 30 to 40 were answered as well as other sections of the paper so there was no indication of candidates running out of time. Comments on Specific Questions Question 2 This produced a rather low 61% correct answers. This is almost certainly not because of the difficulty of the question, but of not considering all the possibilities. Candidates should be encouraged to consider all the options before choosing their answer. Two clear statements need to be written down on the exam paper here. The first needs to be something along the lines of “3000 revolutions in one minute means 50 revolutions in 1 second” and “allowing for 5 pulses takes 0.1 s for the 10 cm across the screen”. This gives the answer of 0.01 s for 1 cm. i.e. 10 ms. 39% of candidates were out by at least a factor of 100. 5 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers Question 11 This was the question on the whole paper with the lowest percentage of correct answers. The candidates did not realise that the horizontal velocity of the ball will also be affected by air resistance. It cannot stay constant over a considerable time but will fall to zero, while the vertical velocity will rise to a constant value. The question states that the ball is affected by air resistance; this cannot be just its vertical motion. Question 13 Only 69% of candidates gave the correct answer. 21% of candidates chose either B or C; diagrams that do not show a resultant force of zero. Question 14 Only half of the candidates were able to write (15 × 3) – (10 × 2) – (5 × 2) = 15 N m in order to obtain the correct answer. Question 17 44% of candidates give the wrong answer, B. Only 36% of candidates could write “m1gv = m2gv + answer”. The kinetic energy distractor here ignores completely any energy input. Question 25 This question produced some unnecessarily poor answers. This type of question is very easy to answer correctly by one simple piece of advice – namely “draw the new wave on the paper as it will appear a short time later”. Candidates are often very reluctant to use the paper itself to write on. Here it becomes abundantly clear that the correct answer is C. At A the water must be moving downwards, yet 33% of candidates put this as their answer. Question 35 This was not very well answered because it was somewhat different from other questions of this type. The voltmeter must read 4 V when the slider is at X. When it moves to Y, potentiometer P and the voltmeter are in series with almost all the resistance in the voltmeter, and hence the p.d. across the voltmeter is still 4 V. Only 21% of candidates realised this. More than half the candidates thought that B was the correct answer. 6 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers PHYSICS Paper 9702/21 AS Structured Questions General comments There were a few candidates who were well-prepared for the examination. Many candidates did not show the skills necessary for them to be successful. Candidates need to be encouraged to improve their recall of standard definitions, laws and equations. With this knowledge, candidates can go on to develop the understanding necessary to apply it. There were many candidates who did not complete their answers to the questions or who left parts of questions completely blank. However, there was no evidence amongst adequately prepared candidates of a shortage of time. Candidates should be advised not to commence any answer by writing out large portions of the question. This is very wasteful of valuable time. Comments on Specific Questions Question 1 Candidates need to learn all the base quantities. They should then be able to express all derived quantities in terms of these base quantities. (a) A minority of candidates were able to give three SI base quantities. Candidates need to be able to recall all the quantities that are fundamental to this course. (b) (i) There were some very poor answers given for the SI base units of force, density and velocity. Some of the answers suggested a lack of understanding of base quantities and derived quantities. (ii) A minority of candidates were able to check the base units in the equation given for the resistive force and obtain a correct answer. Question 2 Candidates need to be aware that the horizontal and vertical motion of a projectile in a gravitational field can be analysed in two separate calculations. (a) (i) A significant number of candidates realised that the horizontal component of the ball’s velocity would remain constant as the ball moved towards the ground. However, very few were then able to use a right-angled triangle to obtain the relationship between the horizontal and vertical components of the velocity at point P. (ii) The application of an equation for constant acceleration was carried out by some of the well- prepared candidates. The majority of candidates did not use the correct component of velocity or were unable to obtain a solution using a valid equation. (iii) The majority of candidates were unable to obtain a correct answer for this problem. There were a number of candidates who did not realise that there was no acceleration in the 7 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers horizontal direction. The intermediate step required a calculation of the time taken to reach point P. This caused difficulty for the majority of candidates. (b) (i) This part enabled some of the weaker candidates to score at least partial credit. The majority realised that the ball would reach a greater horizontal distance. However, further credit was often not awarded owing to poor or inaccurate drawing of the curve. Some of the curves were drawn going upwards at the start and some had the angle the curve made with the ground greater than that of the original. (ii) The majority of candidates were able to score partial credit for a curve that reached the ground before the original. Again further credit was often not awarded owing to poorly drawn curves. Question 3 (a) A minority of candidates were able to give the standard relationship between force and momentum. (b) (i) There were very few correct answers. The main error made by those candidates who knew the correct equation for momentum was to ignore the change in direction of the ball after it made contact with the bar. Other errors made were to mis-read the initial velocity from the graph or to fail to convert the mass into kilograms. (ii) There were very few correct answers. A solution to this problem depended on the candidates obtaining an answer to (b)(i) and knowing the relationship asked for in (a). Only the able and well-prepared candidates completed this part successfully. (c) There were very few correct answers. A number of candidates attempted to obtain an answer using moments. However, the majority did not take moments about a suitable pivot point and/or did not include the weight of the bar. Question 4 (a) This part was straightforward and a significant number of candidates were able to give correct expressions for the majority of quantities. (b) (i) For the majority of candidates who gave the correct expression in (a), this calculation presented few difficulties. The answer being given in the question helped some candidates from making a power-of-ten error. (ii) For the majority of candidates, this calculation caused considerable difficulty. Care should always be taken to ensure that, in numerical questions, the values substituted for quantities have consistent units (usually SI units). If the units used are inconsistent then this often leads to a power-of-ten error in the final answer. (c) Many candidates did not realise that the very small change in resistance was a reason why the method was inappropriate. Question 5 (a) The well-prepared candidates generally gave a correct description. (b) In most scripts, candidates appeared to have the correct ideas but frequently the standard of the drawing meant that credit was lost. Candidates should realise that the wavelength should be clearly shown as unchanged after diffraction at the slit. (c) This straightforward calculation presented a number of difficulties mainly from inconsistent use of SI units. This often led to a power-of-ten error in the final answer. 8 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers (d) There were very few correct answers. Only the well-prepared candidates gave a response to this part. Question 6 (a) (i) For the majority of candidates, this calculation presented few difficulties. (ii) The more able candidates completed the graph with few problems. Candidates should be encouraged to include on the axes of a sketch graph the values that are relevant to any data that is provided or calculated in the question. (b) There were very few correct answers. All three calculations proved to be difficult for most candidates. The calculation of the power dissipation in resistors when the resistors are connected across a power supply in straightforward parallel or series combinations was found to be particularly difficult. Question 7 (a) The attention of candidates should be drawn to the distinction between atom, nucleus, nucleon and nuclide. In this question, it is nuclei that have the same number of protons that should be used to explain isotopes. (b) (i) Very few candidates were able to give more than one correct quantity that is conserved in a nuclear reaction. (ii) Very few candidates were able to apply the conservation laws to the nuclear equation and obtain the correct values. 9 © UCLES 2010 Cambridge International Advanced and Advanced Subsidiary Level 9702 Physics November 2010 Principal Examiner Report for Teachers PHYSICS Paper 9702/22 AS Structured Questions General comments There were some candidates who gave excellent answers to questions and were, quite clearly, well- prepared for the examination. There were many other candidates who did not show the skills necessary for them to be successful. Candidates need to be encouraged to improve their recall of standard definitions, laws and equations. With this knowledge, candidates can go on to develop the understanding necessary to apply it. There were few candidates who did not complete their answers to the questions. There was no evidence amongst adequately prepared candidates of a shortage of time. Candidates should be encouraged to read the questions carefully. Candidates should also be advised not to commence any answer by writing out large portions of the question. This is very wasteful of valuable time. Comments on Specific Questions Question 1 This proved to be a good introductory question with many candidates scoring full credit in (a). (a) (i) The majority of candidates distinguished clearly between vector and scalar quantities. A small minority of candidates concentrated on the requirement of a direction for a vector quantity and omitted the need for a magnitude to describe both quantities. (ii) Most answers were correct. A few candidates incorrectly considered temperature or electrical resistance to be vector quantities. (b) A large number of candidates obtained the correct answer for the tension. The majority of candidates attempted the question by calculation. The most common successful answer resolved the forces in a direction parallel to the slope. Some candi
Recommended
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks