A 14 lb bowling ball is thrown onto a lane with a backspin angular speed of 10 rad/s and forward velocity of 25 ft/s. After a few seconds, the ball starts rolling without slip and forward velocity of 17.2 ft/s and angular velocity of 48.6 rad/s. The ball has a mass moment of inertia of 0.0204 slugs-ft2. Determine the work done by friction on the ball from the initial time until when it starts rolling without slip.

Some material consisting of a collection of microscopic objects is kept at a high temperature. a photon detector capable of detecting photon energies from infrared through ultraviolet observes photons emitted with energies of 0.3 ev, 0.5 ev, 0.8 ev, 2.0ev, 2.5ev, and 2.8ev. these are the only photon energies observed. (a) draw and label a possible energy-level diagram for one of the microscopic objects, which has four bound states. on the diagram, indicate the transitions corresponding to the emitted photons. explain briefly. (b) would a spring–mass model be a good model for these microscopic objects? why or why not? (c) the material is now cooled down to a very low temperature, and the photon detector stops detecting photon emissions. next, a beam of light with a continuous range of energies from infrared through ultraviolet shines on the material, and the photon detector observes the beam of light after it passes through the material. what photon energies in this beam of light are observed to be significantly reduced in intensity (“dark absorption lines”)? explain briefly.