Question

Calculate how many kilometers light travels in space: 1. in a day? 2. in a week? 3. in a month?

Answer 1

1. `2.6xx10^10` `km` per day.
2. `1.8xx10^11` `km` per week.
3. `7.8xx10^11` `km` in a (30 day) month.

Explanation:

Light travels in space at `3.00xx10^8` `ms^-1`, which is `3.00xx10^5` `kms^-1`.

1. In a day there are `60xx60xx24=86,400` seconds in a day. Multiply this by the speed of light to give: `3.00xx10^5xx86400=2.6xx10^10` `km` per day.

2. There are 7 days in a week, so multiply the answer from 1. by 7 to give `1.8xx10^11` `km` per week.

3. It's a bit tricky, because the lengths of months range from 28 to 31 days. Let's use 30 days. Multiply the answer from 1 by 30 to give `7.8xx10^11` `km` in a (30 day) month.