A20-kg wagon accelerates on a horizontal surface at 0.50 m⁄s2 when pulled by a rope exerting a 120-n force on the wagon at an angle of 25° above the horizontal. determine the magnitude of the effective friction force exerted on the wagon and the effective coefficient of friction associated with this force.

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