A100-kg box is placed on a ramp. as one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 25°. what is the coefficient of static friction between box and ramp?

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?