A man strikes one end of a thin rod with a hammer. The speed of sound in the rod is 19 times the speed of sound in air. A woman, at the other end with her ear close to the rod, hears the sound of the blow twice with a 0.19 s interval between; one sound comes through the rod and the other comes through the air alongside the rod. If the speed of sound in air is 347 m/s, what is the length of the rod

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.

Acar traveling at 22 m/s starts to decelerate steadily. it comes to a complete stop in 15 seconds. what is it’s acceleration?

Which of the following are used in an electrochemical cell? a. electrodes b. electrolyte c. terminals d. all of the above