Question

The speed of light in a vacuum is 2.998 × 10 8 8 m/s. How long does it take for light to circumnavigate the Earth, which has a circumference of around 24,900 miles? Do not enter “seconds” as part of your answer.

Answer 1

Answer:- 0.134 seconds

Solution:- The speed is given as $2.988*10^8\frac{m}{s}$ and the circumference is 24900 miles which is same as the distance light have to covered. It asks to calculate the time required to cover this distance by the light.

We need to do unit conversion from miles to meter as the speed is given in meter per second.

1 mile = 1609.34 meter

So, $24900mile(\frac{1609.34meter}{mile})$

= 40072566 meters

Know that, $speed=\frac{distance}{time}$

It's rearranged to time as, $time=\frac{distance}{speed}$

Let's plug in the values in it:

$time=\frac{40072566meter}{2.988*10^8\frac{meter}{second}}$

= 0.134 seconds

So, the light would take 0.134 seconds to travel the mentioned speed. The answer without the unit is 0.134.