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ddd [48]
4 years ago
12

Astronomers can now report that active star formation was going on at a time when the universe was only 20% as old as it is toda

y. When astronomers make such a statement, how can they know what was happening inside galaxies way back then?A. They look at open clusters in our galaxy and extrapolate to the past.B. They look at radio emission from quasars.C. They look at the way galaxy redshifts change with time.D. They examine the spectra of extremely high-redshift galaxies.
Physics
1 answer:
pickupchik [31]4 years ago
8 0

Answer: D.

They examine the spectra of extremely high-redshift galaxies.

Explanation:

Astronomers Measure Redshift and the most accurate way to measure redshift is by using spectroscopy. When a beam of white light strikes a triangular prism it is separated into its various components (ROYGBIV). This is known as a spectrum (plural: spectra).

With an estimated distance of about 32 billion light-years (comoving distance,) or 13.4 GLY (light-travel distance,) astronomers announced it as the mostdistant astronomical  galaxy known

You might be interested in
A basketball player wishes to make a stunning last-second basket. With .8 seconds on the clock, she wants the ball to enter the
zheka24 [161]

Answer:

(1) 46.86^\circ

(2) Diagram has been attached in the solution.

Explanation:

This question is from projectile motion.

From the given question, we will discuss the motion of the basket ball only in the vertical direction from which we will be able to find out the angle of the initial velocity with the horizontal with which it should be shoot to enter the hoop.

Part (1):

Let us assume:

  • y_i = initial position of the basket ball = 2.1 m
  • y_f = final position of the basket ball = 3.05 m
  • a_y = acceleration of the ball along the vertical = -9.8\ m/s^2
  • t = time taken to reach the goal = 0.8 s
  • \theta = angle of the initial velocity with the horizontal
  • u = initial speed of the ball = 7 m/s
  • u_y = initial vertical velocity of the ball = u\sin \theta

Using the equation of motion for constant acceleration, we have

y_f-y_i=u_yt+\dfrac{1}{2}a_yt^2\\\Rightarrow 3.05-2.1=u\sin \theta (0.8) +\dfrac{1}{2}\times (-9.8)(0.8)^2\\\Rightarrow 0.95=7\times \sin \theta (0.8) -3.136\\\Rightarrow 0.95=5.6\sin \theta -3.136\\\Rightarrow 5.6\sin \theta= 0.95+3.136\\\Rightarrow 5.6\sin \theta= 4.086\\\Rightarrow \sin \theta= \dfrac{4.086}{5.6}\\\Rightarrow \sin \theta=0.729\\\Rightarrow \theta=\sin^{-1}(0.729)\\\Rightarrow \theta=46.86^\circ

Hence, the angle of the shoot of the basket ball with the horizontal is 46.86^\circ such that it reaches the hoop on time.

Part (2):

For this part, a diagram has been attached.

4 0
3 years ago
Most new jobs in the United States will be in the _____.
Kazeer [188]

in the service producing sector

6 0
3 years ago
Listed following are the names and mirror diameters for six of the world’s greatest reflecting telescopes used to gather visible
ziro4ka [17]

Answer:

Large binocular telescope, Keck 1 telescope, Hobby-Ebberly telescope, Subaru telescope, Gemini North telescope, Magellan 2 telescope

Explanation:

How much light a telescope can collect depends on its diameter, since in a bigger area more photons will be collected.    

Remember that in a circle the area is defined as:

A = \pi r^{2}  (1)

Where A is the area and r is its radius.

However, the radius can be determined by means of its diameter.

     

d = 2r

r = \frac{d}{2} (1)

Where d is its diameter.

An example of this is when a person is collecting raindrops with a bucket and with a cup. Since the bucket has a bigger area than the cup, it will collect more raindrops by unit of time. In this scenario the raindrops represent the photons.  

   

To determine the light collecting area of each telescope, equation 2 will be replaced in equation 1.

A = \pi (\frac{d}{2})^{2}  (3)

Case for Large binocular telescope:

A_{mirror1} = \pi (\frac{8.4m}{2})^{2}    

A_{mirror1} = 55.41m        

For the second mirror will be the same value

A = A_{mirror1}+A_{mirror2}  

A = 55.41m+55.41m

A= 110.82m

Case for Keck 1 telescope:

A = \pi (\frac{10m}{2})^{2}    

A = 78.53m  

Case for Hobby-Ebberly telescope:

A = \pi (\frac{9.2m}{2})^{2}    

A = 66.47m  

Case for Subaru telescope:

A = \pi (\frac{8.3m}{2})^{2}    

A = 54.10m  

Case for Gemini North telescope:

A = \pi (\frac{8m}{2})^{2}    

A = 50.26m  

Case for Magellan 2 telescope:

A = \pi (\frac{6.5m}{2})^{2}    

A = 33.18m  

Hence, they may be rank in the following way:

Large binocular telescope, Keck 1 telescope, Hobby-Ebberly telescope, Subaru telescope, Gemini North telescope, Magellan 2 telescope.

<em>Key term:</em>

<em>Photons: particles that constitute light. </em>

3 0
3 years ago
The half life of a species that undergoes zero order kinetics is ____ and the rate constant has units of ____.
-BARSIC- [3]
The reaction of the half-life is a description of the needed time for the reactant to deplete.In the first order reactions formula, k is considered as the first order rate constant whose unit is denoted as 1/s. Hope this helps.
6 0
4 years ago
Which substance is an acid ?
DENIUS [597]

Answer:

if you like my answer markme barinlest:)

Explanation:

An acid is a substance or compound that releases hydrogen ions (H+) when in solution. In a strong acid, such as hydrochloric acid (HCl), all hydrogen ions (H+), and chloride ions (Cl-) dissociate (separate) when placed in water and these ions are no longer held together by ionic bonding.

6 0
3 years ago
Read 2 more answers
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