accept an arrow drawn outside the box if it is labelled correctly
1
(iii) equal to
1
(iv) to measure the forces exerted on the dummy during the impact
1
[7]
M35.(a) 3 lines drawnall correctallow 1 mark for each correct lineif two or more lines are drawn from any diagram then all these lines are incorrect
3
(b) (i) horizontal arrow to the right
judge by eye
accept an arrow drawn outside the box if it is labelled correctly
1
(ii) horizontal arrow to the left
judge by eye
accept an arrow drawn outside the box if it is labelled correctly
1
(iii) equal to
1
(iv) to measure the forces exerted on the dummy during the impact
1
[7]
E1. In (a) few candidates used the formula ½mv2 to answer this question.
In (b)(i) many candidates realised the need to use the idea of momentum in this question (though some tried to answer using the formula or kinetic energy); fewer correctly calculated the separate moments of the moving vehicles and fewer still combined these correctly (a common error being to add them rather than subtract them). Most of the candidates who obtained a numerical answer for the total initial momentum were able to calculate a final combined speed consistent with their earlier figure.
In (ii) the idea of a loss of kinetic energy in an inelastic collision (and/or the transfer of kinetic energy e.g. as heat and sound) was seldom stated.
E2. This was not an easy topic but the majority of candidates gained marks in many sections of the question.
(a) This was intended as an easy introduction to the question. Very many candidates who clearly knew momentum was mass x velocity failed to say so in response to this Question and so failed to gain the mark.
(b) In (i)few candidates failed to gain the mark. In (ii)the vast majority correctly calculated the momentum, and then in part (iii)repeated their answer to gain that mark. It was in part (iv)that the weaker candidates began to run into trouble mainly by using a mass of 4 kg and working back to a velocity of 2 m/s. A number of candidates turned the Question on its head at this point; they took the 1600 joules given in part (vi)and used a kinetic energy calculation to find the velocity. They were awarded all three marks. In (v)many candidates quoted the kinetic energy equation and went on to calculate the kinetic energy successfully. Part (vi)presented little trouble to the candidates with energy losses as heat and sound being common.
E3. Part (a) was generally very well answered with very many candidates gaining full marks. When working was shown some candidates used momentum as mass times speed rather than times velocity.
Part (b) proved to be more difficult. The more able candidates gave 14 000/3500 = 4m/s to very quickly gain the five marks. Most other candidates made some creditable start to the problem to gain part marks.
In (c)(i) most candidates correctly answered that the kinetic energy would be reduced. In (ii) many candidates gave a correct energy transfer, the common answer being kinetic energy to sound. However a surprising number of candidates did not refer to an energy transfer, only mentioning the outcome of the transfer. Answers like “sound was given off” were not uncommon. In part (iii) a number of candidates did not answer the question which was concerned with the change of kinetic energy, instead they referred to the total kinetic energy after the collision being greater. Such answers were not credited with the mark.
E4. In part (a) the vast majority of candidates successfully gained both marks for multiplying mass by velocity. Although there were many correct answers to part (b) some candidates lost marks for referring to the momentum of ‘an object’ being the same before and after a collision. A very few answered in terms of the energy before and after the collision and so failed to gain marks. In part (c) very many candidates scored all the marks with correct calculations. There were few part correct answers, those who did not score marks generally lost all the marks through lack of knowledge of the principle of conservation of momentum. A few getting part (i) wrong nevertheless went on to gain full marks in part (ii) by correctly using the incorrect data generated in part (i).
E5. The calculations on momentum were well answered by many candidates, a fair number of whom went on to complete the kinetic energy calculations in part (b).
E6. Most candidates were very familiar with the concept of momentum and answered this question well. However in part (a) a number of candidates assumed the snow was stationary. There were many good answers to part (b), but few correct choices of unit in part (c).
E7. In part (a)(i) many candidates calculated the correct value and gave the correct unit, although very few realised that momentum is a vector quantity and gave the direction. In part (a)(iii) the definition of an elastic collision was not well known, many candidates answering in terms of momentum conservation only. The remaining parts of this question were not well answered, showing a lack of understanding of momentum conservation in part (b) and the effect of momentum change in part (c). Many candidates tried to use moments to explain why the boat tipped rather than moved or answered in terms of force without mentioning momentum. Again, in part (c) very little reference was made to momentum, although some realised the padding was, in effect, a crumple zone and knew that increased impact time would lead to a reduced force. Parts (b) and (c) illustrated the inability of many candidates to apply their knowledge to unfamiliar situations.
E8. In part (a)(i) the majority of candidates understood that an object that isnot moving has zero momentum. Most candidates also realised in part (a)(ii) that the luggage with the largest mass has the most momentum. However, in part (a)(iii) few candidates appreciated that momentum changed when the direction changed. The unit of momentum was generally known.
E9. This question proved to be one of the most demanding on this paper. Many candidates confused momentum with energy in part (a) and few remembered that no external forces should act. In part (b) most had only a sketchy idea of the physics involved and only scored a mark for mentioning the fuel combustion. The most common misconception was that the exhaust gases push against the atmosphere to achieve propulsion. The calculation in part (c) was also poorly attempted. The majority scored a mark for finding the change in velocity but were not able to go on to calculate the mass correctly.
E10. In part (a)(i) most candidates were able to give a partial version of the required equation but few mentioned that this is the total momentum or gave the direction. Many candidates ignored the instructions; for example, in part (ii) they chose examples of collisions and similar events, in part (iii) they gave symbol equations instead of the word equations they were asked for and in part (iv) threw away a mark by failing to state that the trolleys would move to the right after the collision. The examiners did not consider that ‘no forces act’ was a sufficient response in part (v). The response ‘no external forces act’ is quite correct. However it was hardly ever seen. The answer ‘4000 newtons’ was fairly common. However it was often seen as a consequence of some completely false equation such as force = mass + time and consequently received no marks. The examiners are not pleased to note that some candidates are so confused that they think that 0.00625 N or 6.25 N might be the force of a bullet.
E11. (a) (i) Most candidates were able to give a correct version of the required equation.
(ii) Most candidates gave the correct numerical answer in this part. However, only a minority were able to give the correct unit for momentum and most chose to ignore the instruction to give the direction. Consequently many candidates lost the third mark.
(iii) Some candidates showed that they did not appear to understand what was going on, or had not given themselves time to read the whole question and think about it. Rather than repeat their numerical answer to part (a)(ii) they chose to modify it, usually by a factor of two or of ten.
(iv) The equation required in this part was usually stated correctly, although just ‘momentum’ was sometimes erroneously given for ‘change in momentum’.
(v) The calculation for this part was usually correct with the correct unit.
(b) This part revealed that an important application of this equation is not generally related to it. There were some excellent answers which were confident and well expressed. However, many candidates seemed to have a poor understanding of the concept of change of momentum and could not relate it to the time and force they had just referred to. Some claimed that in a crash the momentum of the vehicle is transferred to the passengers, and that your seat belt prevents you from moving, but no one claimed that wearing a seat belt was a bad idea.
E12. Parts (i) and (ii) were usually correctly answered with most candidates giving the correct unit. In part (iii) those who appeared confident that the change in momentum of car A would be equal to the change in momentum of car B were able to proceed to the calculation of car A'’ speed after the impact. Others, who often seemed to have little understanding of this area of the Specification, did not get any marks for this part.
E13. (a) This calculation was not often correct. Many candidates were unable to use the correct pieces of data appropriately. There was widespread confusion between mass and force, and even time and velocity were interchanged in many equations. However, some candidates did complete the calculation well.
(b) Many candidates recognised that there was more air pushed down per unit time or that the air was moving faster. Some candidates confused the air moving faster with the toy moving faster. Although many candidates scored one mark, few candidates were able to link the increased air movement to the subsequent acceleration in order to score both marks.
(c) This was poorly done with most candidates not considering momentum but trying to use their knowledge of polystyrene to answer the question. Many responses centred on the air content of the polystyrene or the air resistance slowing it down on its descent.
E14. (a) (i) Most candidates were able to use the data and equation provided to produce a numerical value for the weight of the toy but there were few responses which stated the correct unit.
(ii) Most of the candidates were aware that the forces involved would need to be balanced to enable the toy to hover.
(b) (i) Most candidates were able to explain the term ‘acceleration’ however, there were many references to ‘move’, ‘increase’ etc without any elaboration.
(ii) This was question was generally answered correctly however, there were a number of incorrect references to ‘south’.
(iii) Half of the candidates understood that the momentum would increase but few could give a valid reason why.
E15. (a) (i) Most candidates stated that velocity is speed in a given direction. Few candidates stated that velocity is either speed in a straight line or velocity = speed × time.
(ii) A good proportion of candidates obtained 64 metres but many candidates correctly obtained 16 and 4 from the graph and then divided the two numbers. Some candidates did a longer calculation and obtained the complete area under the graph.
(iii) This question was well done with the majority of candidates scoring both marks. However some candidates either misread the question and redrew graph 1 or were at least one small square out in their accuracy.
(iv) Many candidates were able to score a mark however the majority simply quoted the law of conservation of momentum.
(b) Many candidates did not score any marks here and wrote about whiplash and trying to avoid serious injuries. Some realised that if the force was to be constant over the same time period then it must be smaller. Some candidates were familiar with the equation linking force and rate of change of momentum but were unable to link this with any logical explanation.
E16. (a) (i) Most candidates were able to identify velocity or speed but weight was often given as an incorrect alternative to mass.
(ii) A pleasing number of correct answers given. However a significant number of candidates tried to complete a calculation that involved total mass and a velocity value.
(b) (i) The substitution of values and the subsequent calculation was handled well by the majority of candidates who scored maximum credit.
(ii) Only a minority of candidates understood that the momentum was conserved.
E17. (a) (i) The calculation was well done with most candidates obtaining 210. However, only half of those obtaining this correct answer were also able to give the correct unit.
(ii) Most candidates who scored 2 or 3 marks for part (a)(i) obtained the correct answer. Those who did not tended to multiply 210 by 0.25 instead of dividing. A number of candidates subtracted 6 or 35 from 210 before dividing by 0.25 thereby losing both marks.
(b) This was either done very well or very poorly. It was not always clear that the rubber tile increased the time to stop and some candidates went straight to the second marking point i.e. increases the time for the change in momentum. Occasionally when a poor answer was written the candidate managed to salvage a mark by finishing with ‘the force is reduced’. A lot of candidates mentioned ‘air gaps’ and ‘bouncing/cushion effect,’ gaining no credit.
(c) The answers were very variable. Many were very vague and referred to accuracy rather than reliability or human error rather than anomalies. The range of thicknesses being insufficient was seldom referred to.
(d) This was generally done well; a few candidates just mentioned recycling without explanation and gained no credit. The most popular answers concerned either burning or use of land-fills, a few candidates mentioned deforestation of rubber trees but these were not penalised!
E18. (a) (i) Most candidates were able to describe the relationship between the maximum height from which a child could fall without serious head injury and the appropriate thickness of rubber safety tiles in a playground.
(ii) The identification from the graph of the correct thickness for a fall of 2m was well done with the second marking point being scored most often by an answer that referred to use of the graph.
(b) (i) Few candidates scored this mark. The vast majority of candidates chose the answer ‘the work done to stop’.
(ii) Just over half of the candidates knew that ‘the force on’ the child would reduced.
E19. (a) Most candidates that correctly chose the skier with the greatest mass as the person with greatest momentum also supplied the appropriate reason for their choice. However a significant minority of candidates chose X or Z and gained no marks.
(b) The majority of candidates were aware that acceleration would produce an increase in the momentum of the three skiers. However there was a large number of candidates that clearly had not read the question correctly and gave answers in terms of an increase in speed.
E20.Foundation Tier
(a) (i) This was well answered with most candidates gaining both marks.
(ii) It is surprising that only just over 50 % of the candidates knew the unit of acceleration.
(iii) For a standard piece of recall it was surprising that only 50 % of candidates scored a mark.
(iv) Less than 50 % of candidates drew the correct line and gained 2 marks. Many candidates did not take into account the final velocity of 9 m/s. Others did not relate the idea of constant acceleration to a straight line.
(b) (i) Candidates that chose the correct shoe of the three on test often gave a suitable reason for their choice to achieve 2 marks, but then failed to appreciate that this shoe was the best on all of the listed types of surface.However nearly 50% of candidates were unable to interpret the bar chart correctly and chose either A or C.
(ii) Most correct answers were in terms of human variability but many candidates mentioned the robot’s consistency. A significant number of candidates did not recognize the importance of the word ‘reliable’ and answered in terms of sensor accuracy.
Higher Tier
(a) (i) Most candidates obtained the correct answer although a few candidates multiplied 9 × 2 instead of dividing.
(ii) The majority of candidates knew that the unit of acceleration was m/s2.
(iii) The majority of candidates gave the correct answer.
(iv) Most candidates produced a straight line with a ruler from the origin to (2,9). Those who did not obtain full marks were generally not accurate enough. A number of candidates did not link the idea of constant acceleration with the need to draw a straight line.
(b) (i) Many candidates correctly chose B but then failed to compare this shoe with both A and C or mention that it was the best shoe on all three surfaces. However a significant number of candidates did score all three marks.
(ii) The majority of candidates obtained the mark, usually giving answers in terms of variations in human athletes eg weight / size of foot may be different and they run at different speeds. A common fault was to be too vague and say that the robots are more accurate or they remove human error; a few answered with the standard response ‘it’s a fair test’ without qualifying the statement.
