An ideal parallel-plate capacitor consists of a set of two parallel plates separated by a very small distance. the capacitor plates are charged to equal and opposite charges ±q and are disconnected from the battery used to charge them. at this point the capacitor is storing an unknown energy u. a point charge of mass m and the same charge as the positive plate (q) is brought against the center of the positively charged plate and released from rest. it accelerates towards the negative plate, striking it with velocity v. in terms of the given quantities (and fundamental constants) what was the energy u stored in the capacitor? a. 1 2 u mv  4 b. 1 2 u mv  2 c. 2 u mv  d. 1 u qv  2 e. u qv  f. none of the abov

Imagine you work as a consultant, and your daily job involves listening to the constructive criticism of others. as part of your job, you must listen to opposing viewpoints to make important decisions. in this activity, you are a consulting dam engineer. you must make a decision about four different dams; should they be repaired, taken down, or left alone? you will listen to contrasting opinions about what should be done with the dams before you make the final decision. as the consulting dam engineer, what do you decide to do with this dam? explain your reasoning. by making your decision, did you support the opinions of the mayor and/or the dam safety official? why or why not? (site 1)

Comedians like to joke that the reason we haven’t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earth’s broadcasts of intellectually embarrassing tv programs, like gilligan’s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. let’s check the assertion that aliens could have been receiving them. tv programs are broadcast at a frequency of about 100mhz with about 100kw of total power in 30frames per second, which emanatesroughly uniformly in all directions. assume that interstellar space transmits these broadcasts without attenuation. no matter how smart they are, aliens would require at least one photon per frame to interpret our signals. findthe number of photons per unit time per unit area reaching a receiver on a possible planet in the nearest star system, which is about 4 light-years away (a light-year is the distance light travels in a year). if aliens aimed a receiver or detector directly at earth, how big (in diameter) would it have to be to receive a photon per frame

Ineed the answer to question 1 , i’m desperate