Physics, 28.01.2020 08:31 murillokiara0kiki
An athlete is working out in the weight room. he steadily holds 50 kilograms above his head for 10 seconds. which statement is true about this situation?
a) the athlete isn’t doing any work because he doesn’t move the weight.
b)the athlete isn’t doing any work because he doesn’t hold the weight long enough.
c) the athlete is doing work because he prevents the weight from falling downward.
d)the athlete is doing work because 50 kilograms is a significant load to lift.
Answers: 2
Physics, 22.06.2019 00:30, WorkingButNotReally
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
Answers: 2
Physics, 22.06.2019 16:40, ashleypere99
Panel bc in fig. p2.76 is semi-circular, with the 3 meter radius and horizontal straight edge through point b. compute (a) the hydrostatic force of the water on the panel, (b) its center of pressure, and (c) the moment of this force about point b. assume atmospheric pressure on the dry side of the panel
Answers: 3
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