Mark Scheme (Results) Summer Pearson Edexcel International Advanced Level in Physics (WPH05) Paper 01 Physics from Creation to Collapse

Transcription

1 Scheme (Results) Summer 06 Pearson Edexcel International Advanced Level in Physics (WPH05) Paper 0 Physics from Creation to Collapse

2 Edexcel and BTEC Qualifications Edexcel and BTEC qualifications are awarded by Pearson, the UK s largest awarding body. We provide a wide range of qualifications including academic, vocational, occupational and specific programmes for employers. For further information visit our qualifications websites at or Alternatively, you can get in touch with us using the details on our contact us page at Pearson: helping people progress, everywhere Pearson aspires to be the world s leading learning company. Our aim is to help everyone progress in their lives through education. We believe in every kind of learning, for all kinds of people, wherever they are in the world. We ve been involved in education for over 50 years, and by working across 70 countries, in 00 languages, we have built an international reputation for our commitment to high standards and raising achievement through innovation in education. Find out more about how we can help you and your students at: Summer 06 Publications Code 46654_MS* All the material in this publication is copyright Pearson Education Ltd 06

3 General ing Guidance All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last. schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions. Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie. There is no ceiling on achievement. All marks on the mark scheme should be used appropriately. All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidate s response is not worthy of credit according to the mark scheme. Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited. When examiners are in doubt regarding the application of the mark scheme to a candidate s response, the team leader must be consulted. Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.

4 Quality of Written Communication Questions which involve the writing of continuous prose will expect candidates to: write legibly, with accurate use of spelling, grammar and punctuation in order to make the meaning clear select and use a form and style of writing appropriate to purpose and to complex subject matter ganise information clearly and coherently, using specialist vocabulary when appropriate. Full marks will be awarded if the candidate has demonstrated the above abilities. Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude others.

5 scheme notes Underlying principle The mark scheme will clearly indicate the concept that is being rewarded, backed up by examples. It is not a set of model answers.. scheme format. You will not see wtte (words to that effect). Alternative correct wording should be credited in every answer unless the MS has specified specific words that must be present. Such words will be indicated by underlining e.g. resonance. Bold lower case will be used for emphasis e.g. and when two pieces of information are needed for mark.. Round brackets ( ) indicate words that are not essential e.g. (hence) distance is increased..4 Square brackets [ ] indicate advice to examiners or examples e.g. [Do not accept gravity] [ecf].. Unit error penalties. A separate mark is not usually given for a unit but a missing or incorrect unit will normally mean that the final calculation mark will not be awarded.. This does not apply in show that questions or in any other question where the units to be used have been given, for example in a spreadsheet.. The mark will not be awarded for the same missing or incorrect unit only once within one clip in epen..4 Occasionally, it may be decided not to insist on a unit e.g the candidate may be calculating the gradient of a graph, resulting in a unit that is not one that should be known and is complex..5 The mark scheme will indicate if no unit error is to be applied by means of [no ue].. Significant figures. Use of too many significant figures in the theory questions will not be prevent a mark being awarded if the answer given rounds to the answer in the MS.. Too few significant figures will mean that the final mark cannot be awarded in show that questions where one more significant figure than the value in the question is needed for the candidate to demonstrate the validity of the given answer.. The use of one significant figure might be inappropriate in the context of the question e.g. reading a value off a graph. If this is the case, there will be a clear indication in the MS..4 The use of g = 0 m s - or 0 N kg - instead of 9.8 m s - or 9.8 N kg - will mean that one mark will not be awarded. (but not more than once per clip). Accept 9.8 m s - or 9.8 N kg -.5 In questions assessing practical skills, a specific number of significant figures will be required e.g. determining a constant from the gradient of a graph or in uncertainty calculations. The MS will clearly identify the number of significant figures required. 4. Calculations 4. Bald (i.e. no working shown) correct answers score full marks unless in a show that question. 4. If a show that question is worth marks, then both marks will be available for a reverse working; if it is worth marks then only will be available. 4. use of the formula means that the candidate demonstrates substitution of physically correct values, although there may be conversion errors e.g. power of 0 error. 4.4 recall of the correct formula will be awarded when the formula is seen or implied by substitution. 4.5 The mark scheme will show a correctly worked answer for illustration only.

6 Question Answer B C A 4 D 5 C 6 D 7 C 8 C 9 A 0 B Total for Multiple Choice Questions 0 Question Answer (a) Use of E mc θ = 0 (K/ o C) Water temperature = 8 o C [Accept K] (b) Example of calculation E mc 600 J 9.7 K kg 400 J kg K o o o 8 C 0 C 8 C Not all of the energy supplied by the heater will be transferred to the water Some of the energy supplied by the heater will be transferred to the surroundings [Accept heat instead of energy, accept lost to surroundings] [Do not accept heater is not 00% efficient] So the (output water) temperature will be lower (than the calculated value) Total for Question 5

7 Question (a) Answer Gmm Use of F r Use of with F = mg F F sun moon 80 [Allow max if only is used to find 8] Example of calculation: F F sun moon m m sun moon r r moon sun kg.80 kg.50 8 m m 8 (b)(i) GM GM g and g (on either side of the Earth s diameter D) x x D (b)(ii) x D (x + D) x So Δg 0 [MP dependent upon MP] The distance of the Sun from the Earth is very large compared with the Earth s diameter Hence the difference in g (at opposite sides of the Earth due to the Sun) is (very) small [MP dependent upon MP] [Accept g is approximately the same at both positions for MP] Total for Question 5

8 Question Answer (a) Age of the universe = /H 0 [Accept age of universe is inversely proportional to H 0 ] Since the measured value of the Hubble constant is smaller, our estimate of the age of the universe is now larger (b)(i) Dark matter cannot be detected via the em-interaction [accept light but do not accept radiation on its own] [accept cannot be seen] (b)(ii) But it has mass But it exerts a gravitational force (The increased proportion of dark matter may mean that) the gravitational force which reduces expansion may be larger the density of the universe may be greater than the critical density (Hence) the universe is more likely to reach a maximum size (before contracting) (Hence) the universe is more likely to be closed [Ignore references to Big Crunch ] Total for Question 6

9 Question 4(a) Answer Use of T m and k f T Correct use of factor 4 in spring constant or mass f =. Hz (accept unit s - ) Example of calculation: k = Nm - = 8 00 Nm - T m 4.kg 0.07 s 800 N m k 4(b) f T 0.07 s.6 Hz Either Acceleration is: (directly) proportional to displacement from equilibrium position (always) acting towards the equilibrium position idea that acceleration is in the opposite direction to displacement (Resultant) force is: (directly) proportional to displacement from equilibrium position (always) acting towards the equilibrium position idea that force is a restoring force e.g. in the opposite direction [accept towards undisplaced point/fixed point/central point for equilibrium position] [An equation with symbols defined correctly is a valid response for both marks. e.g a x or F x ] And (The box undergoes simple harmonic motion because) the springs obey Hooke s law Total for Question 4 6

10 Question Answer 5(a) Use of pv NkT p =. 0 5 (Pa) Example of calculation p NkT V 5(b) Correct use of a factor of J K 9K Pa 8.0 m V = 0.09 m [0.08 m if show that value used] [Ratio method, pv pv can score both marks, for this method apply ecf from ai] For candidates who take the number of molecules that remain in the canister into account: Use of v helium = (50 v balloon + v canister ) V = 0.00 m Example of calculation 5(c) V NkT p Pa J K m There are fewer atoms (in the canister), so the collision rate with the walls decreases [accept molecules but not particles] Hence the (overall) rate of change of momentum is less Therefore there is a smaller force (on the container walls) [dependent upon mp] Total for Question 5 7

11 Question 6(a) Answer 6(b)(i) Reverse temperature scale Approximately logarithmic Correct area identified *6(b)(ii) [Area should include some of the white dwarf stars and not extend as far as the main sequence] (QWC Spelling of technical terms must be correct and the answer must be organised in a logical sequence.) White dwarf stars are the (core) remnant of a red giant star There is no fusion occurring in the white dwarf They have a (relatively) small surface area so they are not very luminous [accept radius for surface area] They are (very) hot, and appear white (because they emit all visible wavelengths) 4 Total for Question 6 7

12 Question 7(a)(i) Answer Resonance is when a system is driven/forced (into oscillation) at its natural frequency (Accept close to its natural frequency) This results in: A maximum energy transfer a maximum/increasing amplitude a maximum efficiency of energy transfer 7(a)(ii) the wavelength is larger (hence the frequency is smaller) 7(b)(i) (Damping is) the removal/dissipation of energy from an oscillation 7(b)(ii) (Hence) there is a decrease in the amplitude As the gel changes size/shape it absorbs energy The gel does not return to its original size/shape So the energy is not returned (to the drum) the energy is dissipated (in the gel) [dependent upon mp or mp] Total for Question 7 8

13 Question 8(a)(i) Answer L Use of F 4 d L = (W) Example of calculation 8(a)(ii) L 4 d Use of L F 4π r T 6 0 m.6 0 Wm W r = m Allow full ecf from (i) [show that value gives.48 x 0 0 m] Example of calculation r L T π Wm K 4 6 W 4000 K 4 8(b)(i) r m (Observed wavelength is less, so) source is approaching Earth v Use of c 5 v m s [accept v = c] [incorrect value of λ in denominator gives v = 7.84 x 0 5 ms - ] 5 - [If v 7.80 ms or v.6 0 c, check denominator; unless substituted then max ] (Observed wavelength is less, so) source is approaching Earth Use of z z = [incorrect value of λ in denominator gives z =.6 x 0 - ] [If z = check denominator; unless substituted then max ] Example of calculation = ( ) nm =.7 nm c v m s.7nm nm m s

14 8(b)(ii) λ B λ Y therefore T B T Y (and statement is incorrect) maxt a constant, so the cooler the star the larger the value of max Wavelength of yellow light is greater than the wavelength of blue light, so statement is incorrect Total for Question 8 9

15 Question 9(a)(i) 9(a)(ii) 9(b) Answer Top line correct Bottom line correct X is a proton 0n 4 6 4N C X 7 We cannot know when a given nucleus will decay We cannot know which nucleus will decay next Pairs of activity and times read from graph for at least half lives and find mean Use A t A 0 e with values from graph and / t / matches values from their graph Example of calculation t = 0 year, A 0 = 40 Bq t = 7500 year, A = 0 Bq 9(c)(i) 9(c)(ii) t / = (7500 year)/ = 58 year The background radiation will increase the recorded count rate Background count rate has to be subtracted (from the count rate) Record count for a longer time Repeat count and find an average

16 9(c)(iii) Use of t ln / Use of A t A 0 e N N 0 e t t = 8650 year Use of Use of / t = 8650 year [Accept 8600 y 8700 y] [.7 0 s] Example of calculation ln t 6000 year / 4 year A A e 0 t 9(d) 0.9 Bq 9.6 Bq (e t 8649year year t The time scale is too long the half life is too short [accept too many half lives have passed] ) *9(e) (So) the activity would be too small to measure (with sufficient accuracy) (Graph shows) the activity will fall to zero after years (After 68 million years), the skull would not have significant carbon content (QWC Spelling of technical terms must be correct and the answer must be organised in a logical sequence.) Binding energy is the energy released when a nucleus is formed the energy required to split a nucleus into its constituent particles Binding energy is not a force We cannot overcome the binding energy [accept idea that it is the strong force that holds the (nucleons in the) nucleus together] Atoms do not undergo fission (nuclei do) Fission is when massive nuclei split into less massive nuclei 4 Total for Question 9 7

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