How long will it take take light moving at 300,000 km/s to reach us from the sun? The sun is 15,000,000 km from earth.

Question

anonymous · Answer

Just use dimensional analysis to see how to approach this. You have a speed in km/s. You have a distance in km. How could you use those two numbers to produce a time, with units of seconds?

t = distance / speed = km / (km / s) = s

anonymous · Answer

$$Time = \frac{ Distance }{Speed}$$

First of all..Here the distance between sun and earth is wrong..It is about:

149,600,000

FACT:THis distance is taken as 1 Astronomical unit;

SPped of light 3 * 10 ^ 5 km

Therefore Time is :

$$\frac{ 1.49  * 10^8}{3 * 10 ^5}$$
$$= \frac{ 1.49 * 10^3 }{ 3 }$$
$$=\frac{ 149 * 10^3 }{3 * 10^2} = \frac{ 149 * 10^1 }{ 3} = 496 seconds= 496/60 = 8.2 minutes[Avg.]$$