A student investigates the forces supporting a metre ruler to determine the weight of the metre ruler. He uses the apparatus shown in Fig. 1.1. The scale of the metre ruler faces upwards. Fig. 1.1 （f）Another student does the experiment with the same equipment．He reads values of $$\(F_{X}\)$$ which are all higher than those in Table 1.1 by 0.05 N ． Suggest one reason for this difference．Assume that the values in Table 1.1 are accurate． . . ［1］ ［Total：11］

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