Question

A space rock is at an average distance of 40 AU from the earth, which is equal to light years.

• A. $5.8\times {10}^{-4}$
• B. $6.32\times {10}^{-4}$
• C. $3.72\times {10}^{-5}$

Answer 1

The correct option is B $6.32\times {10}^{-4}$

Given:
The distance of a space rock from the earth, $d=40AU.$
$1AU=14.96\times {10}^{10}m$ and $1ly=9.46\times {10}^{15}m$
So, $1AU=\frac{14.96\times {10}^{10}}{9.46\times {10}^{15}}ly$
$⟹1AU\approx 1.58\times {10}^{-5}ly$
Hence, $40AU=40\times 1.58\times {10}^{-5}$
$\approx 63.2\times {10}^{-5}ly=6.32\times {10}^{-4}ly$