4   2 A student was given a box of identical glass microscope slides and asked to determine the density of the glass. She used a micrometer to measure the thickness of one of the slides. She repeated this measurement twice in different places and calculated a mean value for the thickness. The thickness of each slide was approximately 1 mm. (a) Explain how she should have measured the thickness of the slides in order to minimise the percentage uncertainty. 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(b) In her report she wrote “My value for the mass of the glass slides was precise, because I measured the mass using an electronic balance which was accurate to the nearest 0.01 g. I reduced the effect of random error by repeating the measurement several times.” Comment on this statement. 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(Total for Question 2 = 6 marks) Turn over 5   3 It was suggested on an online forum that it would be possible to cook a chicken by repeatedly slapping the chicken with one hand. It was claimed that the energy transferred to a chicken in 8000 slaps would be sufficient to raise the temperature of the chicken from 23 °C to 165 °C. In an investigation to test the claim, the effective mass of the hand was taken as 1.75 kg and the speed of the hand just before impact with the chicken as 6.25 m s−1. (a) Deduce whether the data confirms that 8000 slaps would be sufficient. Assume that no energy is transferred from the chicken to the surroundings. mass of chicken = 0.875 kg specific heat capacity of chicken = 1770 J kg−1 K−1 efficiency of energy transfer from the hand = 65% (5) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. (b) Explain whether the assumption made in (a) is realistic. 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(Total for Question 3 = 7 marks)