Distance from Star to Earth: 4.2 Light Years

[thereddevils]

Homework Statement

If the distacne of the star from Earth is 4.2 light years away , how long does it take for light from the star to reach Earth ?

Homework Equations

s=vt

The Attempt at a Solution

4.2 light years = 3 x 10^8 x 3600 x 365.25 x 4.2 m/s

Is my conversion correct ?

 

[HallsofIvy]

But why are you converting "light years" to meters per second?

The definition of "light year" is "the distance light travels on one year".

Light will travel 4.2 light years in 4.2 years!

 

[thereddevils]

But why are you converting "light years" to meters per second?

The definition of "light year" is "the distance light travels on one year".

Light will travel 4.2 light years in 4.2 years!

because the speed of the light is 3 x 10^8 m/s , its in meters per second and i want to make sure that the unit matches ,

it can't be s=vt , 4.2=(3 x 10^8) t ?

 

[Mark44]

The question is a "gimme." To repeat what HallsOfIvy said, it takes 4.2 years for light to travel 4.2 light years.

 

[thereddevils]

The question is a "gimme." To repeat what HallsOfIvy said, it takes 4.2 years for light to travel 4.2 light years.

grrr , dumb me .. thanks