The centre of an observation window in a swimming pool diving pit is an oil sump has a metal hatch cover as shown. the hatch has a mass of 100 kg and is hinged along the left-hand side, about an axis. hh, the sump is fitted with a seal. s, which insures that only the trapezium. hhss, is exposed to the oil pressure of 106 kpa. the hatch is fastened with a pair of bolts. b, along the right-hand side, and the sump is covered by water to a depth of 0.3 m above the hatch surface. the mass centre of the cover is at g. find the tensile force to which each bolt is subjected. note: assume that the underside of the rectangle is exposed to the water pressure at a depth of 300 mm - there is no seal to prevent this.