An airtight box has a removable lid of area 1.80 10-2 m2 and negligible weight. The box is taken up a mountain where the air pressure outside the box is 8.50 104 Pa. The inside of the box is completely evacuated. What is the magnitude of the force required to pull the lid off the box

The nuclear potential that binds protons and neutrons in the nucleus of an atom is often approximated by a square well. imagine a proton conned in an innite square well of length 105 nm, a typical nuclear diameter. calculate the wavelength and energy associated with the photon that is emitted when the proton undergoes a transition from the rst excited state (n 2) to the ground state (n 1). in what region of the electromagnetic spectrum does this wavelength belong?