Question

How long does it take light to reach us from the Sun, 1.53x108 km away? Give your answer in minutes.

Answer 1

Answer:

Sun light takes 8.5 minutes to reach Earth.

Explanation:

Light travels in vacuum at constant speed $c= 3 \times 10 ^8 \cfrac ms$, so we can find the time it takes to travel the given distance from Earth to Sun using a kinematic equation.

Finding the time it takes for Sun light to reach us.

Using the kinematic equation $d = vt$, we can solve for time t, which will give us

$t = \cfrac dv$

We can replace the equation with the given values, but before doing that, we need the values to be on SI units, thus the distance becomes

$d= 1.53 \times 10^8 km \times \cfrac{1000 m}{1 km }\\d = 1.53 \times 10^{11} m$

Replacing the values on the time equation give us

$t = \cfrac{1.53 \times 10^{11} m}{3 \times 10^{8} \cfrac ms}\\t = 510 s$

We get as result 510 seconds, then we must convert them in minutes.

$t = 510 s \times \cfrac{1 min}{60s}\\\boxed{t = 8.5 min }$

So we can conclude that Sun light takes 8.5 minutes to reach Earth.