(a) A teacher, design supervisor, examining a design of a student, point out to him that the shaft of the designed machine was too long and would not have sufficient rigidity. "This can easily be corrected without changing the construction", said the student. "I'l1 take a material of higher quality; make a shaft of alloy steel, i.e., greater yield stress". Was the student right? Explain. (Yes or No alone is not an answer). (b) Figure shows two beams of the same shape and size. Which one is safer to walk over? Explain why? Please note that the two figures are the same.