If a galaxy is traveling away from us at 2.0% of the speed of light, roughly how far away is it?
t= light years
I got 2.4x10^8 light years but its wrong please help me out...thank you
Physics Plz help me - Anon, Monday, May 6, 2013 at 9:17pm
5.98x10^6
Thatz still wrong
Physics Plz help me - bobpursley, Tuesday, May 7, 2013 at 4:23pm
I am wondering what you used for the Hubble constant. Its value is not precise, and in fact, is hotly debated.
Physics Plz help me - Leila, Tuesday, May 7, 2013 at 6:07pm
ya Anon thanks but that is wrong too and bobpursley I am having a hard time figuring this out could you help plz.
To calculate the distance to a galaxy that is traveling away from us at a certain speed, you can use the concept of the Hubble's Law. Hubble's Law states that the recessional velocity of a galaxy is directly proportional to its distance from us.
The equation for Hubble's Law is:
v = H0 * d
where v is the recessional velocity of the galaxy, d is the distance to the galaxy, and H0 is the Hubble constant.
In this case, we are given the recessional velocity (2.0% of the speed of light), and we want to solve for the distance (d). The speed of light is approximately 3 x 10^5 km/s, so 2.0% of the speed of light is 0.02 * 3 x 10^5 km/s = 6 x 10^3 km/s.
Now, the value of the Hubble constant (H0) is not precisely known, and it can vary depending on different measurements and assumptions. However, for the sake of this calculation, let's assume a common value of 70 km/s/Mpc (kilometers per second per megaparsec).
Converting the recessional velocity to kilometers per second, we get 6 x 10^3 km/s.
Plugging these values into the Hubble's Law equation, we have:
6 x 10^3 km/s = (70 km/s/Mpc) * d
Now, we need to solve for d. Rearranging the equation gives us:
d = (6 x 10^3 km/s) / (70 km/s/Mpc)
Calculating this, we get:
d ≈ 85.7 Mpc (megaparsecs)
To convert megaparsecs to light-years, we can use the conversion factor that 1 Mpc is approximately equal to 3.09 x 10^19 km.
So, multiplying the distance in megaparsecs by the conversion factor, we have:
d ≈ 85.7 Mpc * 3.09 x 10^19 km/Mpc = 2.65 x 10^21 km
Finally, to convert kilometers to light-years, we divide by the speed of light, which is approximately 9.46 x 10^12 km/year.
Therefore, the distance to the galaxy is:
d ≈ (2.65 x 10^21 km) / (9.46 x 10^12 km/year) ≈ 2.81 x 10^8 light-years
So the correct answer is approximately 2.81 x 10^8 light-years.