Download SHORT ANSWER. Answer the questions, showingh your work for

SHORT ANSWER. Answer the questions, showingh your work for any calculations.
39) a. Suppose it takes 6 seconds for a 1 kg mass to fall to the ground after being dropped
from the top of a tall building.
39)
a. If there were no air resistance, so that the mass falls with the acceleration of gravity
ge=10 m/s2, about how fast (in m/s) would it be going when it hit the ground?
b. The moon's gravity is 1/6 that of earth. If a 2 kg mass falls for 6 seconds on the moon,
what speed (in m/s) does it reach?
40) Suppose a star four times more massive than our Sun has a planet the same mass as
Earth, orbiting at a distance of 1 AU.
a. What is the orbital period P of the planet (in years)?
b. Recalling that the earth's speed around the sun is 30 km/s, what is the orbital speed
(in km/s) of this planet?
c. How would the above answer change if the planet had twice the mass of earth?
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41) Consider two telescopes with diameters D1= 1 m and D2=10 m.
41)
a. What is the ratio of the telescope areas, A2/A1?
b. What is the ratio a2/a1 of the smallest angle that can be resolved?
42) A star has a surface temperature that is 5 times that of the sun.
a. Recalling that the sun has its spectral energy peak at a wavelength of about 500 nm,
what would be the wavelength (in nm) of peak energy of this star?
b. What is the surface brightness (energy/area/time) of this star compared to the sun,
B/Bsun?
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43) A spectral line that has rest wavelength of 600 nm is observed in the spectrum of a star
to have a wavelength of 600.2 nm.
a. Is the star moving away or toward the observer?
b. What is the fraction, v/c, the star's speed v to the speed of light c?
c. Given that the speed of light is c=300,000 km/s, what is the star's speed in km/s?
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