A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance?

A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance?

Solution:

Given that

The speed of light in vacuum is unity

And we want to find the distance between the Sun and the Earth

Use formula

Distance = speed  × time

Speed is unity = 1 unit /sec

Time = 8 min and 20 sec   = 8 × 60 + 20 sec = 500 sec

Plug the values we get

Distance between Sun and Earth = 1× 500 = 500 units