A set of laminated steel plates is used to form a semi elliptical type leaf spring. The leaf spring thus formed is 0.6m long with each plate thickness and width being 9.5mm and 5 cm respectively. The spring is to carry load of 4500N.Find number of steel plates required if allowable stress in the material is 230MPa. Also find central deflection and radius of curvature if plates are flattened under load. Take E= 200GPa.