八、花青素與類胡蘿蔔素為天然常見的兩類植物性色素，試問其呈色的原理為何？此兩類色素在物理化學性質上又有那些異同？(10分)

1.An I-beam is subjected to a bending moment 5000 N-m and a vertical shear force 1000 N, as shown in Fig-1. The cross section has width b=10cm, height h=12cm, and thickness t=2cm, determine the maximum tensile stress (10%) and the maximum shear stress in the beam. (10%)