A brass wire of diameter d = 2.42 mm is stretched tightly between rigid supports so that the tensile force is T = 98 N (see figure). The coefficient of thermal expansion for the wire is 19.5 × + 10-6 / °C and the modulus of elasticity is E = 110 GPa
(a) What is the maximum permissible temperature drop ΔT if the allowable shear stress in the wire is 60 MPa?
(b) At what temperature changes does the wire go slack?