, 03.12.2019 02:00 gd9075

# We must apply a force of magnitude 83 n to hold the block stationary at x = −2.0 cm. from that position we then slowly move the block so that our force does +4.8 j of work on the spring-block system; the block is then again stationary. what is the block's position x? (there are two answers.)

### Another question on Physics

Physics, 01.02.2019 22:20
Comedians like to joke that the reason we havenâ€™t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earthâ€™s broadcasts of intellectually embarrassing tv programs, like gilliganâ€™s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. letâ€™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