In astronomy distances are often expressed in lightyears One

In astronomy, distances are often expressed in light-years. One light-year is the distance traveled by light in one year. If the distance to a star is 3.5 light-years, what is this distance in meters (There are 365.25 days in one year.) Number Units

Solution

speed of light = 299792458 m/s

Seconds in 1 year = 365.25 day/yr x 24 hr / day x 3600 s/ hr

= 31557600 s

distance traveled in 1 year = speed x time

= 9.461 x 10^15 m

then,

3.5 light year = 3.5 x 9.461 x 10^15 = 3.311 x 10^16 m