Question

The speed of light in a vacuum is 2.998 x 108 m/s. What is its speed in (a) km/h; (b) mi/min?

Answer 1

(a) The speed of light in km/hr is,
`10.7928* 10^8Km/hr`

(b) The speed of light in mi/min is,
`1.117* 10^7mi/min`

Explanation :

(a) We are given the speed of light is,
`2.998* 10^8m/s`

As we know that,

`1m=(1)/(1000)m`

and,

`1s=(1)/(3600)hr`

By using both the conversion, we get:

`2.998* 10^8m/s`

`\Rightarrow (2.998* 10^8m)/(1s)* (3600s)/(1hr)* (1km)/(1000m)`

`\Rightarrow 10.7928* 10^8Km/hr`

The speed of light in km/hr is,
`10.7928* 10^8Km/hr`

(b) We are given the speed of light is,
`2.998* 10^8m/s`

As we know that,

`1m=(1)/(1609.34)mi`

and,

`1s=(1)/(60)min`

By using both the conversion, we get:

`2.998* 10^8m/s`

`\Rightarrow (2.998* 10^8m)/(1s)* (60s)/(1min)* (1mi)/(1609.34m)`

`\Rightarrow 1.117* 10^7mi/min`

The speed of light in mi/min is,
`1.117* 10^7mi/min`