A golf ball with a mass of 46g is hit from the ground with a speed of 20m/s. It takes that ball 1 second to reach its highest point. For all parts assume that the air resistance is negligible. The system includes the golf stick, golf ball, and Earth. I created an energy bar chart attached below. The part where I'm getting stuck is figuring out what is doing the negative work. At first I thought it was the Earth but it can't be because it is part of the system. Then I started doubting my energy bar chart. The final Ug would be mgh so I did m=0.046(covert from g to kg), g=-10, and h=5(figured out using kinematics). The Ug would then be -2.3. But wouldn't it have to be positive 2.3 for energy to be conserved? But at the same time, how can it be positive; g is always negative? So please clear up this problem, I've been stressing on it too much.

Which expression allows you to determine the mechanical advantage of an inclined plane? a. height of plane / input force b. length of plane / input force c. length of plane / height of plane d. height of plane / length of plane

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?