a 25 kg child is initially riding in a 50 kg cart moving at a speed of 2.0 m/s. the child manages to jump off the back of the cart in such a way that he has no final velocity. what is the resulting velocity of the cart? compare the child's change in momentum to the cart's change in momentum. what additional information would be needed in order to determine the force the child used to jump off the cart?​

What happens to light waves from a star as the star moves away from earth?

Which of the following is the result of the nuclear weak force? the instability of large nuclei the repelling force between positively charged protons the structure of the atom certain types of nuclear decay

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.