(ii) An aluminium bar with a circular cross-section of diameter 30 mm and length 1.5 m absorbs 80 J of energy and deform linear elastically upon the application separately of a gradually applied load, sudden load and an impact load that is dropped in the bar from a height of 150 mm. Determine the applied force in the first two cases and the mass of the impacting load in the third case. [The elastic modulus of aluminium is give as 80 GPa). [18]