4. The figure shows a cross section of a submerged tunnel under two immiscible liquids. The top liquid has a specific gravity of SG = 0.5 and thickness h = 15 ft. The bottom liquid has a specific weight of SG2 = 1.5 and thickness h = 40 ft The tunnel has a radius of 20 ft and is 4 miles long. Find the magnitude and location of the resultant hydrostatic force on the circular roof of the tunnel. SG1 SG2 h h2 -R