I need help for this exercise:
Crumple zones in cars increase the time and the distance over the which a car stop during a collision. The length of the crumple zone is 1.6m.
a) Find the maximum speed that the car could have when hitting a wall head-on without subjecting the passager to an acceleration of more than 46.2g (i. e., 46.2 times the acceleration due the gravity)
b) How long would that collision last?

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.

The pressure proportional to the area a- inversely b- directly c- increase d-decrease

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?