Figure 8-21 shows one direct path and four indirect paths from point i to point f . Along the direct...

Figure 8-21 shows one direct path and four indirect paths from point i to point f. Along the direct path and three of the indirect paths, only a conservative force, F_c acts on a certain object. Along the fourth indirect path, both F_c and a nonconservative force F_nc act on the object. The change ?E_mec in the object\"s mechanical energy (in joules) in going from i to /is indicated along each straight-line segment of the indirect paths. What is ?E_mec\". (a) from i to f along the direct path and (b) due to F_nc along the one path where it acts?