# Nanoseconds and Time for Light to Travel

## Homework Statement

The problem asks how many nanoseconds does it take for light to travel 1km in a vacuu?

## Homework Equations

I know that 1KM is equal to 1000 meters or 10^3. I also know that 1ns is equal to 10^-9s and light travels at about .3m per ns.

## The Attempt at a Solution

I'm not sure where to start with this problem. I know I have to convert the two givens but im stuck at where to start. I started to think that I could divide the .3m per ns by 10^9 and then multiply it by 10^3. If someone could help me figure out how to start this problem and a push in the right direction that would be highly appreciated. Thanx in advanced.

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Galileo
Homework Helper
You probably remember:
distance = velocity x time

so

time = distance/velocity.

for constant velocity. So use that.
You can always get the right relation by considering the units on both sides if you don't see it right away.