2.58) Knowing that a 0.5-mm gap exists when the temperature is 24°C. determine (a) the temperature at which the normal stress in the aluminum bar will be equal to -75 MPa, (b) the corresponding exact length of the aluminum bar. 0.5 mm K 350 mm 450 mm Bronze A = 1500 mm² E = 105 GPa a = 21.6 X 10-6°C Fig. P2.58 and P2.59 Aluminum A = 1800 mm² E = 73 GPa a = 23.2 x 10-6°C 2.59 Determine (a) the compressive force in the bars shown after a tem-