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

`0.6709* 10^9miles/hour`

Step-by-step explanation:

We have given speed
`=2.998* 10^8m/sec`

We know that 1 km = 1000 m

So
`2.998* 10^8m=(2.998* 10^8)/(1000)=2.998* 10^5km`

And 1 miles = 1.609 km

So
`2.998* 10^5km=(2.998* 10^5)/(1.609)=1.8632* 10^5miles`

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

So 1 sec
`=(1)/(3600)=2.777* 10^(-4)hour`

Now speed
`=(distance)/(time )=(1.8632* 10^5)/(2.777* 10^(-4))=0.6709* 10^9miles/hour`