A cylindrical riser must be designed for a sand-casting mold. The casting itself is a steel rectangular plate with dimensions 7:5 cm x 12:5 cm x 2:0 cm. Previous observations have indicated that the total solidification time (TTS) for this casting = 1.6 min. The cylinder for the riser will have a diameter-to-height ratio = 1.0. Determine the dimensions of the riser so that its TTS = 2.0 min