An iron rim is to fit snugly on a cylindrical iron rod at 20○c the diameter of the rod is 6.445cm and the inside diameter of the rim is 6.420cm, to sleep over the rod the rim must be slightly larger than the rod diameter by about 0.008cm. To what temperature if it holes is to be large enough so that it will sleep over the rod? the linear expansion of the iron is alpha=12×10^-6/○c.