A blue billiard ball (2kg) with initial speed 6m/s Collides with another red billiard ball (3kg) moving in the same positive x-axis. After the collision, the first ball bounces off with speed √4m/s in a direction that makes an angle +30 with the original direction. The second ball bounces in a direction that makes an angle θ2 on the other side of the first ball’s original direction. Neglect friction. Use the x-y coordinate system shown.

(a) what’s the value of θ2?

(b) determine by mathematical whether the collision was elastic or inelastic

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.