"A thin rod of cross-sectional area A is bent into the shape of a semicircle with radius R and lays flat in the xy-plane. The quadrant 1 portion has a mass of M,while the arc in quadrant 2 has a mass of 2M/3. (a) Draw a picture and label pertinent information. determine center of mass by integration. (b) if a straight rod length of 2R of similar cross section and mass M is now fitted along the x-axis between the ends of the semicircular rod then what is the center of mass of the new system.