A particular person's eardrum is circular, with a diameter of 8.50 mm. (a) How much sound energy (in ) is delivered to an eardrum in one second, at the threshold of human hearing? (The threshold of human hearing is taken to be 1.00 X 10-12 W/m2.) (b) How much sound energy (in )) is delivered to an eardrum in one second, at the pain threshold for human hearing? (The pain threshold occurs at 1.00 W/m , one trillion times as intense as the lowest audible level.) (c) Assume that musicians onstage are exposed to sound that is 10 decibels below the human pain threshold. Over the course of a two-hour concert, how much sound energy (in )) does each ear absorb onstage?(d) Assume that the amplifiers on the stage operate at a combined power of 5,000 Watts, and that 80% of this is converted to sound.

In the future, people will only enjoy one sport: electrodisc. in this sport, you gain points when you cause metallic discs hovering on a field to exchange charge. you are an electrodisc player playing the popular four disc variant. the disks have charges of qa = −8.0 µc, qb = −2.0 µc, qc = +5.0 µc, and qd = +12.0 µc. (1) you bring two disks together and then separate them. you measure the resulting charge of these two disks and find that it is +5.0 µc per disk. which two disks did you bring together? (a) a and b (b) a and c (c)a and d (d)b and c(e) b and d (f) c and d. (2) you bring three disks together and then separate them. you measure the resulting charge of these three disks and find that it is +3.0 µc per disk. which three disks did you bring together? a, b, and c (a) a, b, and d (c) a, c, and d (d) b, c, and d. (3) given the resulting charge of each disk measured in (b) is +3.0 µc, how many electrons would you need to add to a disk of this charge to electrically neutralize it? electrons