Aperson, with his ear to the ground, sees a huge stone strike the concrete pavement. a moment later two sounds are heard from the impact: one travels in the air and the other in the concrete, and they are 0.90 s apart. the speed of sound in air is 343 m/s, and in concrete is 3000 m/s. how far away did the impact occur?

An aircraft performs a maneuver called an "aileron roll." during this maneuver, the plane turns like a screw as it maintains a straight flight path, which sets the wings in circular motion. if it takes it 35 s to complete the circle and the wingspan of the plane is 11 m, what is the acceleration of the wing tip

Idon’t quite understand this problem

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.