Mark Scheme (Results) January 2021 Pearson Edexcel International GCSE In Physics (4PH1) Paper 2PR

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Question number Answer Notes Marks 1 (a) (i) B – QR; 1 A is not correct as the substance is a solid C is not correct as the substance is a liquid D is not correct as the substance is boiling (... ii) A – PQ; 1 B is not correct as the substance is part solid, part liquid C is not correct as the substance is a liquid D is not correct as the substance is boiling (iii) any irregular, spaced out collection of particles; 1 (iv) D – they move quickly and randomly; 1 A is not correct as this is how particles in a solid move B is not correct as only particles at 0 K can theoretically be stationary C is not correct as this is how particles in a liquid move (b) (i) thermometer; allow temperature sensor, temperature probe 1 (ii) 80 (°C); 1 (c) temperature difference = 27 (°C); 3 substitution; allow ECF from incorrect temperature difference evaluation; 37296, 10080 = 2 marks e.g. ∆T = 37 - 10 = 27 (°C) energy = 1.2 × 840 × 27 (energy =) 27000 (J) allow 27216, 27220, 27200 (Total for Question 1 = 8 marks)Question number Answer Notes Marks 2 (a) (i) centre of gravity / centre of mass; allow centre of weight 1 (ii) balance / newtonmeter; allow newton scales 1 ignore scales (b) (i) moment = force × (perpendicular) distance; allow standard symbols and rearrangements e.g. moment = F × d 1 ignore m for moment (ii) substitution; 1 e.g. 0.68 × 4.3 (= 2.924 Ncm) (iii) idea that anti-clockwise moment = clockwise moment; stated or implied by working 3 rearrangement; evaluation; allow ECF from (ii) e.g. 2.9 = F × 11 F = 2.9 / 11 (F =) 0.26 (N) allow 0.2636…- 0.2658… allow 0.27 condone 0.263 (Total for Question 2 = 6 marks)Question number Answer Notes Marks 3 (a) (to the) left; allow towards A, away from B ignore backwards 2 (because) repulsion (due to like magnetic poles); reject if mention of charge (b) (i) 0.045 (kg m/s); allow ‘the same’ 1 (ii) momentum of B after collision = 0.045 – (-0.021); 2 evaluation; allow 0.024 for 1 mark e.g. 0.045 - −0.021 allow 0.045 + 0.021 (momentum =) 0.066 (kgm/s) (iii) substitution into F = change in momentum / time taken; allow ECF from (ii) 2 evaluation; use of 0.024 from (ii) gives 0.126… (N) e.g. F = 0.066 / 0.19 (F =) 0.35 (N) allow 0.347… (N) (iv) (to the) right; allow towards B, away from A 1 (Total for Question 3 = 8 marks)Question number Answer Notes Marks 4 (a) (i) speed = frequency × wavelength; allow standard symbols and rearrangements e.g. v = f × λ 1 (ii) determination of period; 5 conversion from ms to s; evaluation of frequency; substitution into v = f × λ; allow ECF from incorrect frequency evaluation of speed; -1 for POT error 175, 700 (m/s) = 3 marks e.g. period = 4 squares period = (4 × 1 =) 4 ms allow 0.004 (s) frequency (= 1/4 × 10-3) = 250 (Hz) speed = 1.4 × 250 speed = 350 (m/s) (b) any five from: ignore descriptions of different experimental methods 5 MP1. reference to reaction time; allow description of reaction time issues MP2. suggestion that light flash and sound may not be at the same time; MP3. idea that distance is too short (to give accurate value); MP4. idea that ruler is not appropriate to measure this distance; allow suggestion that trundle wheel/tape measure should be used MP5. idea of mis-counting the number of ruler lengths; MP6. idea of zero error on ruler; MP7. idea of ruler not going in a straight line; allow ground not being level MP8. idea of lack of repeats; MP9. idea that time of travel is too short to be measured by a human; [Show More]

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