A brass rod is long and an aluminum rod is long when both rods are at an initial temperature of . The rods are placed in line with a gap of between them. The distance between the far ends of the rods is maintained at throughout. The temperature is raised until the two rods are barely in contact. The coefficients of linear expansion of brass and aluminum are and , respectively. In the figure, the temperature at which contact of the rods barely occurs, in , is closest to:
