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Question: 

A light-year is the distance light travels in one year (at speed $= 2.998 \times 10^8 \textrm{ m/s}$).

  1. How many meters are there in 1.00 light-year?
  2. An astronomical unit (AU) is the average distance from the Sun to Earth, $1.50 \times 10^8 \textrm{ km}$. How many AU are there in 1.00 light-year?

Source: Giancoli, Douglas C., Physics: Principles with Applications, 7th Edition, 2014.

Quick Answer: 

a) $9.46 \times 10^{15} \textrm{ m}$
b) $6.31 \times 10^4 \textrm{ AU}$

Giancoli 7th Edition, Chapter 1, Problem 19

(1:50)