The half-life of iodine-131 is 8 days. chan hee examines two samples of iodine-131. sample 1: 10 g sample 2: 20 g what can chan hee expect to observe about the samples after 16 days? a. the mass of iodine-131 in sample 1 will be 7.5 g and in sample 2 will be 16 g. b. three-fourths of each sample will have undergone radioactive decay. c. ten grams of each sample will have undergone radioactive decay. d. one-half of each sample will still be iodine-131.

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

Acar drives toward the right over the top of a hill, as shown below. which arrow represents the centripetal acceleration? w x y z

What are the north and south poles of a solenoid change with?