T. {10p} In the middle of e horizontally positioned closed tube is e h = 20 cm long oolumn of Hg {Figure 4]. Each side of the tube entrepe e i = I15 111 column of air. The atmospheric pressure is H = 1m irPa. When the tube is held irertlosillzlr the oolumn oi Hg slides down with d = It] on. By how much the column of Hg slide down from the middle of the tube if: {a} One end of the horizontally positioned tube is open {bl One end of the Vertically positioned tube is open. Figure 4