If the speed of light is equal to 3×108ms−1, how many kilometers will make up 1 light year?
One light year is the distance travelled by light in one earth year, that is in 12 months, or 365 days.
Therefore time taken =365×24×60×60=31536×103 s
Speed of light =3×108 ms−1
1 light year = speed of light x time =3×108×31536×103=9.46×1015 m =9.46×1012 km