A particle of mass m is in lowest-energy (ground) state of the infinite potential energy well At time t = 0, the wall located at x = L is suddenly pulled back to a position at x = 2L. This change occurs so rapidly that instantaneously the wave function does not change. Calculate the probability that a measurement of the energy will yield the ground-state energy of the new well.

What is the probability that a measurement of the energy will yield the first-excited energy of the new well? Describe the procedure you would use to determine the time development of the system. Is the system in a stationary state?