A bar is attached to the spring at the point C. The left end of the bar is pin supported and can rotates about the pin at Point A. The mass of the bar is m=20kg. The total length of the bar is LAB=3m and LAC=2m. Point A is 0.6 m below the ceiling. A clockwise constant couple moment M= 30Nm is applied on the bar so that the bar rotates from the horizontal position with θ=0° to the vertical position with θ=90°. The spring always maintains at the vertical position. The spring’s stiffness coefficient is k=30N/m and its unstretched length is 0.5 m. The acceleration due to gravity g=9.81 m/s2. During the process that the bar rotates from the horizontal position (state 1) to the vertical position (state 2), determine the following.  5) when use T to represent kinetic energy, V potential energy, U work done and if the bar is at rest at state 1,  the principle of work-energy in this case could be expressed as____________ .       V1+∑U(1-2)=T2+V2     T1+V1=T2+V2     T1+∑U(1-2)=V2     ∑U(1-2)=T2+V2

A bar is attached to the spring at the point C. The left end of the bar is pin supported and can rotates about the pin at Point A. The mass of the bar is m=20kg. The total length of the bar is L_AB=3m and L_AC=2m. Point A is 0.6 m below the ceiling. A clockwise constant couple moment M= 30Nm is applied on the bar so that the bar rotates from the horizontal position with θ=0° to the vertical position with θ=90°. The spring always maintains at the vertical position. The spring’s stiffness coefficient is k=30N/m and its unstretched length is 0.5 m. The acceleration due to gravity g=9.81 m/s². During the process that the bar rotates from the horizontal position (state 1) to the vertical position (state 2), determine the following.

 5) when use T to represent kinetic energy, V potential energy, U work done and if the bar is at rest at state 1,  the principle of work-energy in this case could be expressed as____________ .