Pierre conduit une voiture à vitesse constante sur une portion d’autoroute rectiligne. Il parcourt 450 m pendant une durée égale à 9500 ms. Puis, à la même vitesse, il aborde un virage en arc de cercle. 1. Calculer la vitesse de Pierre dans : a) Le référentiel lié à la voiture. b) Le référentiel lié à la route. 2. Quelle est la trajectoire de Pierre dans le référentiel lié à la route ? 3. En déduire la nature du mouvement de Pierre dans ce même référentiel.

Which statement best describes how private industry decides where to spend the money on research and development

How is coal extracted from mountaintop removal mines? a. dynamite is used to create underground tunnels where miners go to extract the coal. b. dynamite is used to break apart rocks and then draglines are used to remove the broken rock and reach the coal. c. coal in mountaintops is extracted by digging strips in the landscape to reach the coal. d. placer deposits in mountain river bottoms are removed by

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.