Determine the minimum fluidizing velocity of the catalyst for 1800 kg of the catalyst in a tubular fluid bed reactor with a radius of 0.5 m, given that the optimum conversion reaction occurs when the bed volume is 1.64 the volume of the catalyst particles. The fluid density and viscosity are 980 kg/m3 and 3.8 mPas, respectively, while the particle density is 2800 kg/m3.