The speed of light in a vacuum is exactly 299,792,458 m/s. This speed is sometimes used to provide a convenient yardstick for large astronomical distances.(c) A light-year is the distance light travels in one year. The Sun is 28,000 light-years from the center of the Milky Way galaxy. What is this distance in meters?

Respuesta :

Answer:

[tex]\\2.647191386*10^{20}m[/tex]

Explanation:

To answer this question it is necessary to understand that Light travels in vacuum at a constant speed, which means an important property to estimate distances in Universe. We already know that speed of light in vacuum is exactly 299,792,458 m/s.

To solve this question, we need to answer these two ones:

  1. What is the distance that light travels in one year?
  2. How many seconds are there in a year?

In the first question, we need to know the distance that light travels in one year, which give us some clue to respond the distance that light travels in 28,000 light-years.

The answer to the second question it is crucial to answer the first question in meters.

How many seconds are there in a year?

[tex]\\ 1year = 365 days * \frac{24h}{day}*\frac{60min}{h}*\frac{60s}{min}=31,536,000s[/tex].

That is, there are 31,536,000 seconds in a year.

What is the distance that light travels in one year?

Because light travels at a constant speed, the distance can be calculated as follows:

[tex]\\ Speed = \frac{distance}{time}[/tex]

or, equivalently,

[tex]\\ distance = Speed * time[/tex]

So,

[tex]\\ distance = 299792458\frac{m}{s} * 31536000s [/tex]

But, we can see that these are big numbers, and a better way to deal with this is to use scientific notation or floating-point numbers.

Then,

[tex]\\ 299792458\frac{m}{s} = 2.99792458 * 10^{8}\frac{m}{s}[/tex]

and,

[tex]\\ 31536000s = 3.1536000*10^{7}s[/tex]

So,

[tex]\\ 2.99792458 * 3.1536000 = 9.45425495 [/tex], and,

[tex]\\ 10^{8}*10^{7} = 10^{8 + 7} = 10^{15}[/tex]

Then, the total distance that light travels in a year is:

[tex]\\ 9.45425495 * 10^{15}m[/tex]  

But we now that The Sun is 28,000 light-year from the center of the Milky Way galaxy, and that  28000light-year= [tex]\\2.8 *10^{4}[/tex] light-year.

So, the distance in meters of The Sun from the center of the Milky Way galaxy is:

[tex]\\9.45425495 * 10^{15}m * 2.8 *10^{4}light-year =26.47191386*10^{15}*10^{4}=26.47191386*10^{15+4}=26.47191386*10^{19}=2.647191386*10^{20}m[/tex]

Then, the answer is:

[tex]\\2.647191386*10^{20}m[/tex].  

Likewise, the answer could be found as a matter of proportions, mostly because light travels the same distance at each time:

If light travels [tex]\\ 9.45425495 * 10^{15}m[/tex] in a light-year, how many meters does light travel in 28,000 light-year?

[tex]\frac{9.45425495* 10^{15}m}{light-year}[/tex] = [tex]\frac{X meters}{2.8*10^{4}light -year}[/tex]. or

[tex]\\ X =\frac{9.45425495* 10^{15}m}{light-year} * {2.8*10^{4}light -year}=2.647191386*10^{20}m[/tex]

That is, the same result.

Notice that we calculate the result using 1 year = 365days. We can add more precision to our answer if we consider 1 year = 365,25days, following the same steps.