Question

It takes time 8 min for light to reach from the sun to the earth surface. If speed of light is taken to be $3\times {10}^{8}m{s}^{-1}$, find the distance from the sun to the earth in km.

Answer 1

Given:
Time = 8 min
Speed = $3\times {10}^{8}m{s}^{-1}$
Time is not given in the standard from, i.e., in seconds.

So first convert to seconds;
$1min$ = $60s$
$8min$ = $8$ $\times$ $60s=480s$
Distance $=s$ $\times$ $t$
= $3\times {10}^8\times 480$

$=1.44\times {10}^{8}km$