WJEC Physics for AS Level Student Book 2nd Edition

7 About this book For example, look at the following questions: Unit 1 Exam practice questions, Q3: all 10 marks are practical marks. Unit 2 Exam practice questions, Q4: the 6 marks in Q4(b) are practical marks. Issues questions The definition of AO3 refers to issues. This includes ethical judgements, how scientists validate new discoveries, how science informs society’s decisions and the costs, risks and benefits of the application of scientific knowledge. Examples of this type of question are: Unit 1 Exam practice questions, 3(d) – costs and benefits of knowledge Unit 2 Exam practice questions, 1(c) – benefits, risks and ethical judgement. You should be aiming to use your scientific knowledge to make reasoned comments. Error carried forward (ecf) If you look at a WJEC physics mark scheme, you will come across the letters ecf, which stand for error carried forward. You will find this when a calculation uses a value which you have just calculated in an earlier question part – which might be incorrect. You will not be penalised further if you use this value. Example: Question 2 of the Unit 1 Exam practice questions. (b) (i) Calculate the strain in the rubber at point B . [1] (ii) Determine the Young modulus of the rubber in the region AB . [3] The calculation of the Young modulus depends upon the value of the strain, so you can still get 3 marks for part (ii) even if your answer to (i) was wrong. Command words used in WJEC exam questions These are words which give you information about what sort of answer is required. There are quite a few command words – here are the most common ones: State Give a value or statement without any explanation. Example: State the Principle of Moments. Answer: For a body in equilibrium under the action of a number of forces, the sum of the clockwise moments (of the forces) about any point is equal to the sum of the anticlockwise moments about the same point. This example shows the value of becoming familiar with the WJEC Terms and Definitions booklet. Describe Write a short account with no explanation. Example: Describe the motion shown in the YíW graph between 0 and 30 s . Answer: 0–10 s : constant velocity of 15 m s í1 . 10–30 s : constant acceleration to 35 m s í1 Experimental methods can also be asked for using this command word. Explain You need to give a reason or reasons. Example: Explain why the skydiver falls at a constant velocity. Answer: Because the upward force of air resistance on her is exactly equal (and opposite) to the downward force of gravity. Calculate You should use one or more equations together with data to find the value of an unknown quantity. Determine This word is used when the calculation requires more than just the application of an equation. Example: Unit 1 Exam practice questions, 2(b). To answer part (ii) you have to relate the graph to the equation E = ı İ Discuss and Evaluate These command words are often used in AO3 questions, e.g. in the context of deciding which (if either) of two statements is likely to be correct. Your aim should be to provide good application of physics together with a final judgement. Example: Unit 1 Exam practice questions, Q1(c). These command words are also used in the concluding parts of a practical skills question. Example: Evaluate whether the data are consistent with the relationship y = kx , where k is a constant. In this case, the evaluation would consist of deciding whether the data were consistent with a straight-line graph through the origin and whether the degree of scatter in the data points made for a confident conclusion. Suggest This word indicates that there is no single correct answer. It often occurs as the last part of a structured question and it involves using knowledge gained from the specification and applying it creatively to additional material. Example: Unit 1 Exam practice questions, Q3(d). The earlier parts of the question are about the properties of subatomic particles and are testing knowledge and the ability to apply the knowledge. This part includes a degree of speculation. In answering this kind of question, be prepared to have an opinion and to use it.