28. a flea jumps by exerting a force of 1.20 × 10−5 n straight down on the ground. a breeze blowing on the flea parallel to the ground exerts a force of 0.500 × 10−6 n on the flea while the flea is still in contact with the ground. find the direction and magnitude of the acceleration of the flea if its mass is 6.00 × 10−7 kg . do not neglect the gravitational force.

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.

Which lists the pairs of plates in order from least to greatest in terms of the work done to move the electron?

Steelhead trout migrate up stream to spawn.occasionally they need to leap up small waterfalls to continue their journey. fortunately, steelhead are remarkable jumpers, capable of leaving the water at a speed of 8.0 m/s. a. what is the maximum height a steelhead trout can jump? b.leaving the water at 8.0 m/s, the trout lands on top of the water fall 1.8 m high. how long was it in the air?