There is a cylindrical shape sweet potato with an initial uniform temperature of 25°C and it has an average diameter of 70 mm and length of 150 mm. Thermal conductivity and diffusivity of the sweet potato are 0.62 W/m · °C and 0.2 x 10-6 m2/s, respectively. It is to be cooled by refrigerated air at 1.8°C. The average heat transfer coefficient between the potato and the air is 25 W/m2 · °C. Determine how long it will take for the center temperature of the potato to drop to 5.5°C.

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