This unit conversion example problem demonstrates how to convert the speed of light in meters per second to miles per hour.
Problem
The speed of light in a vacuum is 2.998 x 108 m/sec. What is this speed in miles per hour?
Solution
To convert this measurement, we need to convert meters to miles and seconds to hours. To do this, we need the following relationships:
1000 meter = 1 kilometer
1 kilometers = 0.621 mile
60 seconds = 1 minute
60 minutes = 1 hour
We can now set up the equation using these relationships so the units cancel out leaving only the desired miles/hour.
speedMPH = 2.998 x 108 m/sec x (1 km/1000 m) x (0.621 mi/1 km) x (60 sec/1 min) x (60 min/1 hr)
Note all the units cancelled out, leaving only miles/hr:
speedMPH = (2.998 x 108 x 1/1000 x 0.621 x 60 x 60) miles/hr
speedMPH = 6.702 x 108 miles/hr
Answer
The speed of light in miles per hour is 6.702 x 108 miles/hr.