Question

The brass bar and the aluminum bar in the drawing are each attached to an immovable wall. At 29.8 °C the air gap between the rods is 1.48 x 10^-3 m. At what temperature will the gap be closed?

Answer 1

a=alpha

the expansion of the aluminum is

dL_AL =a_ALL_AdT ---------1

the expansion of the brass dL_B =a_BL_BdT--------2

adding 1+2 gives

dT =(1.48*10^-3)/(23*10^-6*1+19*10^-6*2)

dT=24.3^oC

The desired temperature is

T=29.8+24.3=54.1^oC