A. Show that the shape functions for the given element are correct. B. Derive the stiffness matrix for a Bar Element with four nodes 5--1 5 5-1 1 2 3 9 S (51), $ = -27/7 (5+1) (4 + 1) (-1), S = 7/6(+1) (4 + }) (* - } }) 16 9 S.--2 (4+) (4-1)(4-1), s, -27 (5+1)(5-) (5-1) S 16 16