## Physics Technology Update (4th Edition)

$Time~elapsed=2.57s$
From Earth to the Moon $= 2.39\times10^{5}mi$ From Earth to the Moon and back = $2\times2.39\times10^{5}mi=4.78\times10^{5}mi$ $Time~elapsed=\frac{distance}{average~speed}=\frac{4.78\times10^{5}mi}{1.86\times10^{5}mi/s}=2.57s$