WJEC Physics for AS Level: Revision Workbook

Q16 Rhian is given a rectangular block of iron and asked to determine its density. These are her measurements: length / cm 6.35, 6.38, 6.34, 6.38, 6.37 width / cm 4.26, 4.24, 4.28, 4.17, 4.25 height / cm 2.79, 2.81, 2.83, 2.80, 2.81 mass / g 599.5 (a) Rhian thinks that she made a mistake with one of her measurements, so decides to ignore it. Identify the suspect measurement and give a reason. 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(b) In calculating the uncertainty in her value for the density of the iron, Rhian decides to ignore the uncertainty in the mass measurement. Evaluate her decision. 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(c) Use the data to calculate a value for the density of iron together with its absolute uncertainty. 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Q17 Maurice is given a uniform half-metre rule, a 100 g mass and a piece of cord and asked to measure the mass, m , of a piece of metal. He suspends the 100 g mass from the 1.0 cm mark and balances the ruler on the edge of a pencil. The balance point is 15.0 cm. pencil He replaces the 100 g mass with the piece of metal. The balance point is now 12.5 cm. Use these results to determine the mass of the piece of metal. 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Section 1 Basic physics | 17 Unit 1 Practice questions