What Is the Speed of Light in Miles Per Hour

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 kilometer1 kilometers 0.621 mile60 seconds 1 minute60 minutes 1 hourWe 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/hrspeedMPH 6.702 x 108 miles/hr Answer The speed of light in miles per hour is 6.702 x 108 miles/hr.