(Solved): All necessary equations must be embedded within the related problems. Please solve correctly. 4. ( ...

All necessary equations must be embedded within the related problems. Please solve correctly. 4. ( \( \mathbf{2 5} \) pts) Consider the linear elastic stepped bar shown below. Assume only gravitational force acting on it. (a) Solve for nodal displacements by using the direct approach or the principle of minimum potential energy. (b) Solve for displacement by using hand calculation (i.e., "axial loading" that you have learned in mechanics of materials). Is there a large difference between hand calculation and finite element method? State why or why not.