(3 complete sentences) Explain why placing wheels under a heavy box reduces the necessary force required to push it along at a constant speed. Please describe the types of friction (static, sliding, kinetic, rolling, or fluid) this is showing and how it is different from other types of friction.

An electron is trapped at a defect in a crystal. the defect may be modeled as a one-dimensional, rigid-walled box of width 1.00 nm. (a) sketch the wavefunctions and probability densities for the n 1 and n 2 states. (b) for the n 1 state, nd the probability of nding the electron between x1 0.15 nm and x2 0.35 nm, where x 0 is the left side of the box. (c) repeat (b) for the n 2 state. (d) calculate the energies in electron volts of the n 1 and n 2 states