Charge g is distributed in a spherically symmetric ball of radius a. (a) evaluate the average volume charge density p. (b) now assume p(r) is directly proportional to r. (i) derive the formula for p(r) in terms of r, q, and a. at what value of r does p(r)= ? [ans: 340] (ii) find q(r), and graph it.

Answer quickly (15 points) a comet is approaching earth. describe earth’s gravitational pull as the comet gets closer to it. a. remain constant b. increase c. decrease d. reversed

First, launch the video below. you will be asked to use your knowledge of physics to predict the outcome of an experiment. then, close the video window and answer the question at right. you can watch the video again at any point. part a as in the video, we apply a charge +q to the half-shell that carries the electroscope. this time, we also apply a charge –q to the other half-shell. when we bring the two halves together, we observe that the electroscope discharges, just as in the video. what does the electroscope needle do when you separate the two half-shells again? view available hint(s) as in the video, we apply a charge + to the half-shell that carries the electroscope. this time, we also apply a charge – to the other half-shell. when we bring the two halves together, we observe that the electroscope discharges, just as in the video. what does the electroscope needle do when you separate the two half-shells again? it deflects more than it did at the end of the video. it deflects the same amount as at end of the video. it does not deflect at all. it deflects less than it did at the end of the video. submit

To fully describe the photoelectric effect, scientists must consider which of the following to be quantized? o a. both light and matter o b. matter only o c. light only o d. neither light nor matter