In which of the following frames does Newton’s 1st law of motion apply (There is no change in motion without force)? The upper surface of a plank translating on a floor with friction)
The horizontal plane of an accelerating lift )
The vertical plane of an accelerating lift )
A braking bus)

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?