Mark Scheme for a Materials Test, Schemes and Mind Maps of Antenna Theory and Analysis

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Materials – General Mark Scheme

Question 1

Question 1 Materials — General Mark Scheme (a) @ (ii) (iii) the extension produced (by a force) in a wire is directly proportional to the force applied ¥ applies up to the limit of proportionality or elastic limit VW elastic limit: the maximum amount that a material can be stretched (by a force) and still return to its al length when the force is removed W (or correct use of permanent deformation) the Young modulus: ratio of tensile stress to tensile strain V unit: Pa or Nm? ¥ (b) @ (ii) length of wire ¥ diameter (of wire) ¥ graph of force vs. extension ¥ reference to gradient Y gradient = EA/] ¥ (or graph of stress vs. strain, with both defined and gradient = E) area under the line of F vs. e ¥ Total 11 Question 2 (a) returns to original length/shape/position/state/zero extension/no permanent extension ¥ (b) (12 to 14 big squares/318 small squares + 8 area of 1 big square = 10N x 0.05m = 0.50/small = 2 = 0.01 = 0.02) statement of method that refers to area V accept triangle if area is mentioned 5.0 to 8.0 (J) or clear attempt to calculate correct area v triangle OK here 5.1 (J) for single triangle is max 2 6.0 to 7.0 me v (c) e=)"v ( =r ASL 10 x 0.50 5.0 x 1076 x 0.04 () Y also gets first mark use of 50 (N) and 0.04 (m) giving T. 25 x 108 (Pa) gains 2 marks use of 5(N) and 0.4 (m) is max 2 2.5 x 10" (Pa) v (d) straight line through origin finishing at the same point as the rubber + 1 small division ¥ (d) (ii) point beyond which graph is no longer linear or force no longer proportional to extension or Hooke’s law limit ¥ Total 10