As you work with a block and tackle, you seem to be working hard, so you decided to investigate. You know that a force of 2000 N is needed to lift the object. You measure your exerting force of 400 N as you pull the rope down 6 m to lift the weight a distance of 1 m. What is the efficiency of the block and tackle?

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?