Final answer:
When the potential energy of the particle is 8 J in simple harmonic motion, the particle is at its maximum displacement from equilibrium, denoted as x = xm.
Step-by-step explanation:
The question involves understanding the energy transformation in simple harmonic motion (SHM), specifically the oscillation of kinetic and potential energy as an object moves along the x-axis. Because the total energy is conserved in a system undergoing SHM, knowing the potential energy at any point allows for the determination of its position. In this scenario, the given potential energies 3 J and 8 J must correspond to points along the oscillation where the total mechanical energy (sum of kinetic and potential) remains constant.
When the potential energy is given as 3 J, and the kinetic energy is 5 J, the total mechanical energy is 8 J. As the potential energy increases to 8 J, the kinetic energy becomes zero because the total energy is conserved. This scenario occurs only at the turning points where the amplitude is maximum, ±xm. Therefore, when the potential energy of the particle is 8 J, the particle is at x = xm, which corresponds to the maximum displacement from equilibrium.