A student determined the Young modulus of a material in the form of a wire. The student hung a reference wire and the wire being tested from the ceiling. At the lower end of the reference wire he positioned the fixed part of a vernier scale. The student attached a 100 g mass hanger to the wire being tested. The initial reading on the vernier scale was 0.0 mm , as shown. He added masses to the mass hanger and measured the corresponding extension $$\(\Delta x\)$$ of the wire using the vernier scale. (i) The student kept his feet away from the apparatus so that the masses could not fall on his feet. Explain one other safety precaution. (2) .............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. (ii) Each time the student added more mass, $$\(\Delta x\)$$ increased by a few mm. Explain why he should measure $$\(\Delta x\)$$ using a vernier scale, instead of a metre rule. (2) .............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. ..............................................................................................................................................................................................................................................

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