Question

If a star were 2 light years away, how far is it?

2 trillion kilometers
11.76 trillion kilometers
18.92 trillion kilometers
18.92 kilometers

Answer 1

2 trillion kilometer

Answer 2

Answer: 18.92 trillion kilometers

Explanation:

One light year is the distance traveled at the speed of light in one year.

Speed of light in vacuum =
`3* 10^8m/s`

Thus distance traveled by light in one year =
`3* 10^8* 60* 60* 24* 365=9.46* 10^15m`

Hence, distance traveled in two years =
`2* 9.46* 10^15=1.89* 10^(16)m=18.92* 10^(12)km=18.92 trillionkm`

(1km=1000m)
`(1trillion=10^(12))`