问一道量子力学的题
Consider a particle of mass in the state |n> of a box of length L.Find the force F=-dE/dL（偏微分,那个符号打不出来用d代替了）encountered when the walls are slowly pushed in ,assuming the particle remains in the nth state of the box as its size changes.Consider a classical particle of energy En in this box.Find its velocity,the frequency of collision on a given wall,the momentum transfer per collision,and hence the average force.Compare it to -dE/dL computed above.