Consider a perfectly reflecting mirror oriented so that solar radiation of intensity I is incident upon, and perpendicular to, the reflective surface of the mirror. If the mirror has surface area A, what is Frad, the magnitude of the average force due to the radiation pressure of the sunlight on the mirror? Express your answer in terms of the intensity I, the mirror's surface area A, and the speed of light c.
Frad =
To solve the second part of this problem you will need to know the following:
the mass of the sun, Msun=2.0×1030kg, the intensity of sunlight as a function of the distance, R, from the sun,
Isun(R)=3.2×1025WR2,
and
the gravitational constant G=6.67×10−11m3/(kg⋅s2).
Suppose that the mirror described in Part A is initially at rest a distance R away from the sun. What is the critical value of area density for the mirror at which the radiation pressure exactly cancels out the gravitational attraction from the sun?
Express your answer numerically, to two significant figures, in units of kilograms per meter squared.

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

What is the most useful equation for electric power?

Two objects of different mass start from rest, are pulled by the same magnitude net force, and are moved through the same distance. the work done on object 1 is 900 j. after the force has pulled each object, object 1 moves twice as fast as object 2. how much work is done on object 2?