Answer
U = 5.00 J
Work Step by Step
From the previous question, we got that at x = 2.00 m, K = 9.00 J. Since only conservative forces are acting on the particle, the mechanical energy $E_{mec}$ is conserved. Initially at x = 5.00 m, the particle had K = 14.0 J and U = 0 J, and therefore $E_{mec}$ = K + U = 14.0 J + 0 = 14.0 J. At this later moment, $E_{mec}$ must also equal 14.0 J. Since K = 9.00 J, we must have U = 5.00 J.
