What Is The Speed Of Light In Miles Per Hour?

Unit Conversion Example Problem

Format
mla apa chicago
Your Citation
Helmenstine, Todd. "What Is The Speed Of Light In Miles Per Hour?" ThoughtCo, Mar. 16, 2017, thoughtco.com/speed-of-light-in-miles-per-hour-609319. Helmenstine, Todd. (2017, March 16). What Is The Speed Of Light In Miles Per Hour? Retrieved from https://www.thoughtco.com/speed-of-light-in-miles-per-hour-609319 Helmenstine, Todd. "What Is The Speed Of Light In Miles Per Hour?" ThoughtCo. https://www.thoughtco.com/speed-of-light-in-miles-per-hour-609319 (accessed October 23, 2017).
You can use a laser to measure the speed of light yourself.
Nick Koudis, Getty Images

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.

Format
mla apa chicago
Your Citation
Helmenstine, Todd. "What Is The Speed Of Light In Miles Per Hour?" ThoughtCo, Mar. 16, 2017, thoughtco.com/speed-of-light-in-miles-per-hour-609319. Helmenstine, Todd. (2017, March 16). What Is The Speed Of Light In Miles Per Hour? Retrieved from https://www.thoughtco.com/speed-of-light-in-miles-per-hour-609319 Helmenstine, Todd. "What Is The Speed Of Light In Miles Per Hour?" ThoughtCo. https://www.thoughtco.com/speed-of-light-in-miles-per-hour-609319 (accessed October 23, 2017).