C1C2C3 03 properties of materials

C123 Jan 2012 6 3 A company wants to make rulers from a polymer. The company wants to know if the polymer is suitable for this job. Scientists test sample rulers made from this polymer. They use this apparatus. G-clamp plastic ruler wooden strip O bench distance mass M wooden blocks The scientists hang a mass, M, from the end of each sample. They measure the distance that each ruler bends. Their results are shown in the table. distance ruler bends in mm sample 1 sample 2 sample 3 sample 4 sample 5 sample 6 34 32 34 35 33 36 (a) The apparatus contains a horizontal wooden strip. Explain why this is important. .............................................................................................................................................. [1] C123 Jan 2012

7 (b) (i) The scientists make sure that mass M is the same size for each sample. Explain why this makes it a fair test. ...................................................................................................................................... [2] (ii) State one other factor that should also be kept the same for each sample. ...................................................................................................................................... [1] (c) (i) The true value for the distance the ruler bends lies within a range. What is this range? The range is from to mm. [1] (ii) Work out a best estimate for the distance the ruler bends. best estimate = mm [2] (iii) How likely is it that your best estimate is the true value for the distance the ruler bends? Use the data to explain your answer. ...................................................................................................................................... [2] C123 Jan 2012 Turn over

C123 Jan 2012 8 (d) The company want the rulers to be more flexible. Suggest how the polymer could be made more flexible. Explain how this makes the polymer more flexible. The quality of written communication will be assessed in your answer. .............................................................................................................................................. [6] [Total: 15] C123 Jan 2012

9 4 Most tennis racquets are made from a polymer reinforced with carbon fibres. Nanotechnology is used to make better tennis racquets. Nanoparticles are added to fill gaps in the reinforced polymer. (a) Explain the meaning of the term nanotechnology. .............................................................................................................................................. [2] (b) Suggest how these new tennis racquets are better than those that do not contain nanoparticles. .............................................................................................................................................. [1] (c) Nanoparticles are used in a wide variety of products. Some scientists are worried about this. Which two statements give reasons for their concern? Put ticks (✓) in the boxes next to the two correct answers. Nanoparticles do not occur in nature. Nanoparticles have a smaller surface area than larger particles. The effects of nanoparticles have not yet been fully investigated. Nanoparticles are larger than 1000 nm. Nanoparticles may be harmful to health. Nanoparticles are too small to be seen by the unaided eye. [2] [Total: 5] C123 Jan 2012 Turn over

Each rope has the same thickness and the same length. 8 3 A company plans to make a new rope for sailing boats. The new rope must be strong and quite stretchy. Scientists working for the company test ropes made from five polymers, A, B, C, D and E. They want to know which is the best polymer to use. They measure how much each rope stretches as a load is applied to it. They do this until the rope breaks. Each rope has the same thickness and the same length. Their results are shown in the graph. Each line ends when the rope breaks. 60 A 50 B 40 C stretch in cm 30 20 D E 10 500 1000 1500 2000 2500 3000 3500 4000 mass in kg (a) Each rope must have the same thickness and length to make it a fair test. Explain why. .............................................................................................................................................. [2] © OCR 2012

9 (b) Use the graph to decide which of these statements are true and which are false. Put ticks (✓) in the correct boxes to show your choices. True (✓) False (✓) None of the polymers stretch. The polymer that supports the biggest mass breaks at 3000 kg. All of the polymers can support a mass of 1500 kg. The polymer that supports the biggest mass stretches the least for a mass of 1500 kg. [2] (c) (i) All five lines on the graph show the same pattern. Finish this sentence to describe the pattern. As the mass , the polymer stretches [1] (ii) The graph shows differences between the polymers. Give two differences. 1 2 [2] (d) The company chooses to make the new rope from polymer C. Suggest why they use this polymer rather than any of the others. .............................................................................................................................................. [3] [Total: 10] C123 June 2012 Turn over

8 4 A company decides to make fence posts from a plastic. The company makes and tests 100 fence posts with the same size and shape. They measure how far each post bends under the same conditions. The bar chart shows their results. 25 20 15 number of posts 10 5 1 2 3 4 5 6 7 8 9 10 11 12 bend in cm (a) (i) In the test, how many posts bent 9 cm or more? ............................................ [1] (ii) The company wants to make 500 posts each day. They will not sell posts that bend 9 cm or more. How many posts will they reject each day? Show your working. number of posts rejected = [2] C123 Jan 2013

9 (b) The polymer used to make the posts has a wide range of flexibility. Which statements give an explanation for this? Put ticks (✓) in the boxes next to the two best statements. The polymer does not have any cross-linking. Plasticizer has mixed unevenly in the polymer. Only one type of monomer has been used to make the polymer. Too much plasticizer has been added to the polymer. Different batches of the polymer have different chain lengths. All of the polymer molecules are very long. [2] Question 4 continues on the next page C123 Jan 2013 Turn over

10 (c) The company decides that the plastic they have is too flexible and has too large a range of flexibility. Technicians test small pieces of three other plastics. All the samples used have exactly the same size. They measure how far each sample bends under the same conditions. Their results are shown in the table. Distance sample bends in mm Sample number 1 2 3 4 5 6 mean Plastic A 35 33 35 34 34 33 34 Plastic B 14 13 14 15 13 15 14 Plastic C 10 18 12 14 17 13 14 Describe the advantages and disadvantages of each plastic for making fence posts. Which plastic would you choose and why? The quality of written communication will be assessed in your answer. .............................................................................................................................................. [6] [Total: 11] C123 Jan 2013

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