Asolid sphere of radius r rotates about a diameter with an angular speed ω. the sphere then collapses under the action of internal forces to a final radius r/2. what is the final angular speed of the sphere

Sort the images based on whether there's a force of attraction or repulsion between the magnets shown. attraction repulsion

Could we see a galaxy that is 20 billion light-years away?

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?