Question

A light-year is _________. a. about 10 trillion kilometers the time it takes light to travel around the Sun b. about 300,000 kilometers per second the time it takes light to reach the nearest star

Answer 1

Answer:

about 10 trillion kilometers

Explanation:

c = Speed of light = $3\times 10^8\ m/s$

t = Seconds in one year = $365.25\times 24\times 60\times 60$

1 Light year

$1\ ly=ct\\\Rightarrow 1\ ly=3\times 10^8\times 365.25\times 24\times 60\times 60=9.46728\times 10^{15}\ m\\ =9.46728\times 10^{15}\times 10^{-3}\\ =9.46728\times 10^{12}\ km\approx 10\ trillion\ km$

The answer is a. about 10 trillion kilometers