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## Homework Statement

A new unit of length is chosen such that the speed of light in a vacuum is unity. What is the distance between the sun and the earth in terms of the new unit, if light takes 8 mins and 20 sec to cover this distance?

## Homework Equations

A new unit of length is chosen such that the speed of light in a vacuum is unity. What is the distance between the sun and the earth in terms of the new unit, if light takes 8 mins and 20 sec to cover this distance?[/B]

## The Attempt at a Solution

Sol-

The speed of light in vacuum (c) = 1 (new unit of length s–1 ) Time taken by light to reach the earth t = 8 min + 20 s = (8 × 60 + 20) s = 500 s ∴ Distance between the sun and the earth = Speed of light × Time x = c × t = 1 (new unit of length s–1 ) × 500 s = 500 new unit of length

*here I don't understand why C = S^-1. Could you explain, please?