At the beginning of systole, when ventricular pressure exceeds atrial pressure, the AV valves close. However, initially the semilunar valves also remain closed since ventricular pressure is still not sufficiently strong enough to force them open (consequently at this point in the cardiac cycle there is no blood flow into or out of the ventricles). This phase is known as . A) isovolumetric relaxation (phase 4)
B) isovolumetric contraction (phase 2)
C) ventricular ejection (phase 3)
D) ventricular filling (phase 1)

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