2. A water reservoir as shown in Figure 2 has the width of x = 100 m, length of y = ABC m, and the depth of the reservoir is given by z = 50 m. (ABC is the lest 3 digits of your new matrio number). The density of the water can be approximated by p(z) = a b x z where a = 993 kg m'3 and b = 0.05 kg m\" i.e. at the surface (2 = 0} the water has density 998 kg m3 (oorresponding to a temperature of 20 \"C while 50 m down i.e. z = -40. the water has a density of 1000 kg m'3 {corresponding to the lower temperature of 4 \"C. {i} Find the total mass of water in the reservoir. (ii) Estimate the total work is needed to empty the water reservoir? Figure 2 A reservoirs partially lled with water (9 markahir marks)