Hint: Velocity V -, Acceleration = (35 marks) 1 (b) With reference to a Cartesian coordinate system Oxyz , the temperature inside the sphere x + y' + z? =9 is given by T(x, y,z) =1+ ax? +3y +2z? . At the point (-1,2, 2) on the sphere, the rateof change of the temperature per unit distance along direction perpendicular to the sphere is zero. Find the constant a . (35 marks) 2 . Let S be the portion of the surface z - $ = x + 4x + y for 2