A book rests on a table. The force of gravity pulls down on the book with a force of 20 newtons. What prevents the books from accelerating downward at 9.8 m/sec2 A) The table presses back up on the book with an equal and opposite force of 20 newtons.
B) The table and the book together are accelerating downwards at 9.8 m/sec2
C) The table presses back up on the book with a force greater than 20 newtons.
D) The inertia of the book holds it up

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?