Two vectors, in three dimensions, are given in cartesian coordinates as :
a=(8,8,9)
and
r=(4,9,5)

using these vectors, determine the angle between these two vectors in radians

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?