Ateacher pulls a box of books on a horizontal floor with a force of 290 n directed 40.9 degrese above the horizontal. the coefficiant of kinetic friction between the box and the floor is 0.184. the mass of the box and books is 44.5 kg. draw a free body diagram. what is the normal force that the floor exerts on the box? calculate the acceleration of the box

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.

What can you increase the strength of an electromagnet by

In which type of system is power held solely by the central government and not shared with regional governments? group of answer choices federal unitary confederate oligarchic