Question

The speed of light in a vacuum is 2.998×108 m/s. Calculate its speed in miles per hour (miles/h). Express the speed in miles per hour to four significant digits.

Answer 1

Answer:

$0.6709\times 10^9miles/hour$

Explanation:

We have given speed $=2.998\times 10^8m/sec$

We know that 1 km = 1000 m

So $2.998\times 10^8m=\frac{2.998\times 10^8}{1000}=2.998\times 10^5km$

And 1 miles = 1.609 km

So $2.998\times 10^5km=\frac{2.998\times 10^5}{1.609}=1.8632\times 10^5miles$

Now we know that 1 hour =60×60=3600 sec

So 1 sec $=\frac{1}{3600}=2.777\times 10^{-4}hour$

Now speed$=\frac{distance}{time }=\frac{1.8632\times 10^5}{2.777\times 10^{-4}}=0.6709\times 10^9miles/hour$