Question

Light from the sun reaches Earth in 8.3 min. The velocity of light is 3.00 108 m/s. Given this info, how would you determine how far the Earth is from the sun?

Answer 1

Velocity is defined as the rate of travel, and can be found using the distance formula.

velocity=

distance

time

Rearranging this formula we can solve for distance given velocity and time of travel.

d=vt

We are given velocity and time, and so can solve for distance, but if we plug in the values given;

d=(3.00×108m/s)(8.3minutes)

We can see that the units do not match up. Since seconds are the SI unit for time, we will need to convert 8.3 minutes to seconds.

t=(8.3minutes)(60seconds/minute)=(498s)

Now our units work out and we can solve for distance.

d=(3.00×108m/s)(498s)

d=1.49×1011m