A mass of 11.0kg is suspended from a rigid support by an aluminium wire of
              length 2.0m, diameter 2.0mm and Young’s modulus 7.0 x 1011 Nm-2. Determine
              the extension produced.

              [g = 10ms-2;  =]

 A popular question but not well attempted.  Though most candidates were able to recall the fomular for Youngs modulus they could not make the extension, e, the subject of the formula.  Many could hardly handle the substitution, conversion of units, standard form and the arithmetic processes involved.