Question

A light-year is the distance that light travels in one year. the speed of light is 3.00 × 108 m/s. how many miles are there in one light-year? (1 mi = 1609 m, 1 y = 365 d)

Answer 1

One of the basic equations in physics is Speed = Distance/Time. Thus,

Distance = Speed*Time

Time = 1 light-year * 365 days/yr * 24 h/day * 3,600 s/h = 31536000 seconds
Distance = (3×10⁸ m/s)*(31536000 s) = 9.4608×10¹⁵ meters

Convert meters to miles:
Distance = 9.4608×10¹⁵ m * 1 mile/1,609 m = 5.88×10¹² miles