# the speed of light is 3.0x10^8 m/s. how long does it take light to reach the earth from the sun, which is 1.5x10^11m away?

## Expert Answers This question can be solved using the classic equation of motion: distance = velocity * time.  We have two known parameters and one unknown parameter; however, in order to solve the problem we must first rearrange the equation to solve for time: time = distance / velocity.

distance = 1.5x10^11m
velocity = 3.0x10^8 m/s

Substituting into the equation:

time = (1.5x10^11m)/( 3.0x10^8 m/s) = 500 seconds

Therefore, light travelling at 3.0x10^8 meters per second takes 500 seconds (8 minutes, 20 seconds) to reach the Earth, which is 1.5x10^11 meters away from the sun.

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