Question

If the speed of light is `3.0` `times` `10^8` `m``/``s`, and the distance from the Sun to Earth is about `1.5 times 10^11` `m`, how long does it take sunshine to reach Earth?

Answer 1

The time is about 500 s.

Explanation:

Speed is `"distance"/(time)`, so after a bit of algebra we can see that,

`time = "distance"/"speed"`

Plugging in the data

`time = (1.5*10^11 m)/(3.0*10^8 m/s)`

Cancelling and simplifying,
`time = (1.5*10^3 cancel(m))/(3.0 cancel(m)/s) = 0.5*10^3 s ~= 500 s`

I hope this helps,
Steve