4. A 5.0 g marble is fired vertically upward using a spring gun. The spring must be compressed 8 cm if the marble is to reach a target 20 m above the marble’s position on the compressed spring. (a) What is the change ∆Ug in the gravitational potential energy of the marble-Earth system during the 20 m ascent? (b) What is the change ∆Us in the elastic potential energy of the spring during it’s launch of the marble? (c) What is the spring constant of the spring?

Find the momentum for a 2.6-kg brick parachuting straight downward at a constant speed of 8.4 m/s .

A10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead, which is much denser than aluminum. which one has the greater buoyant force on it? explain. b - the aluminum a) both have the same buoyant force. b) the aluminum c) the lead d) it cannot be determined without knowing their volumes.

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?