A 1.83 m-long aluminum "singing" rod is held in the center by one hand and is stroked along the direction
of the rod by the other. The Young's modulus for Al is
7.00 × 1010 N/m7 and the diameter of the rod is 1.27
cm. If the rod is subjected to a force of 10.5 N, what
is the tensile stress on the rod?

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