9. 5 points SerCP8 21.P050 18 (a) The distance to a star is approximately 5.80 x
ID: 1445544 • Letter: 9
Question
9. 5 points SerCP8 21.P050 18 (a) The distance to a star is approximately 5.80 x 10 m. If this star were to burn out today, in how many years would we see it disappear? years (b) How long does it take for sunlight to reach Venus? minutes (c) How long does it take for a microwave radar signal to travel from Earth to the Moon and back? (d) How long does it take for a radio wave to travel once around the Earth in a great circle, close to the planet's surface? (e) How long does it take for light to reach you from a lightning stroke 11.0 km away? Need Help? L Read t Talk to a Tutor My NotesExplanation / Answer
a) speed of light, c = 3 x 10^8 m/s
distance of star, d = 5.80 x 10^18
we will see it when light reaches to us.
time taken by light to reach us = d /c = 1.9333 x 10^10 s
T (in years) = (1.933 x 10^10 ) / (3600 x 24 x 365) = 613.06 years
b)distance between Venus and earth, d = 41.4 x 10^9 m
t = d/c = 138 sec
t( in min) = 138 / 60 = 2.3 min
c) Distance between moon and earth d = 3.703 x 10^8 m
time taken to reahc and return , t = 2d/c = 2.47 sec
d) distance, d = 2 pi r
t = (2 x pi x 6371 x 10^3 ) / (3 x 10^8) = 0.133 sec
e) d = 11 x 10^3 m
t = (11 x 10^3) / (3 x 10^8) = 3.667 x 10^-5 sec
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