The expected answers are
(a)                     Stress = Force
                                        Area
       =                    50          
                      3.142 (l x 10-3)2

        =                 1.59 x 107 Nm-2
(b)        Strain = extension
                           length
       =               25 x 10-5
                            5
      
      =         5.0 x 10-5

This numerical problem on the elastic property of materials was not popular among the candidates. The performance was also very poor. The candidates were given adequate data from which they were expected to calculate the stress and the strain in a wire.

While most of the candidates were able to correctly recall the equations for stress and strain, they lost substantial marks due to their inability to correctly

(i)  manipulate reciprocals and values in standard form;

(ii) convert unit