Question

A thick, vertical iron pipe has an inner diameter of 0.070 m. A thin aluminum (α = 23x10-6 (C°)-1) disk, heated to a temperature of 89°C, has a diameter that is 4.4x10-5 m greater than the pipe's inner diameter. The disk is laid on top of the open upper end of the pipe, perfectly centered on it, and allowed to cool. What is the temperature of the aluminum disk when the disk falls into the pipe? Ignore the temperature change of the pipe.