a) Calculate the minimum velocity at which spherical particles of density 1600 kg/m and of diameter 1.5 mm will be fluidised by water in a tube of diameter 10 mm on the assumption that the Carman-Kozeny equation is applicable. (7 marks) b) Discuss the uncertainties of calculation in 3 a) above. (1 mark) c) Repeat the calculation in 3 a) above using the Ergun equation (5 marks) d) Explain the differences in the results obtained in 3 a) and 3 c) above. (1 mark) (14 marks)