Answers: 1
Physics, 22.06.2019 00:30
Comedians like to joke that the reason we havenââŹâ˘t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earthââŹâ˘s broadcasts of intellectually embarrassing tv programs, like gilliganââŹâ˘s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. letââŹâ˘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
Answers: 2
Physics, 22.06.2019 06:00
The frequency of vibrations of a vibrating violin string is given by f = 1 2l t Ď where l is the length of the string, t is its tension, and Ď is its linear density.â (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and Ď are constant) (ii) the tension (when l and Ď are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is â f is â (ii) when the tension is increased by turning a tuning peg df dt 0 and t is â f is â (iii) when the linear density is increased by switching to another string df dĎ 0 and Ď is â f is â
Answers: 3
Physics, 22.06.2019 06:50
Much of the information taught in earth-space science would not be available if it werenât for our remote sensing abilities. explain two ways our remote sensing strategies contribute to our knowledge of these topics.
Answers: 3
Physics, 22.06.2019 10:30
Astone weighing 1.5 kilograms is resting on a rock at a height of 20 meters above the ground. the stone rolls down 10 meters and comes to rest on a patch of moss. the gravitational potential energy of the stone on the moss is joules.
Answers: 1
The leads from the pharynx towards the lungs...
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