E. Galaxy Cluster
Explanation:
A galaxy cluster, or cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by mutual gravity.
A megaparsec is a million parsecs and there are about 3.3 light years in a mega-parsec. Parsec is rather a natural distance unit for astronomers. The standard abbreviation of a mega-parsec is Mpc.
A parsec is approximately 3.09 x 1016 meters, a megaparsec is about 3.09 x 1022 meters.
Hence, 8 megaparsecs is gigantic size and that can be only of a galaxy cluster consisting of hundreds and thousands of galaxies bounded together.
Keywords: galaxies, parsec, megaparsec, galaxy cluster
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Answer:

Explanation:
Given:
- mass of John,

- mass of William,

- length of slide,

(A)
height between John and William, 
<u>Using the equation of motion:</u>

where:
v_J = final velocity of John at the end of the slide
u_J = initial velocity of John at the top of the slide = 0
Now putting respective :


<u>Now using the law of conservation of momentum at the bottom of the slide:</u>
<em>Sum of initial momentum of kids before & after collision must be equal.</em>

where: v = velocity with which they move together after collision

is the velocity with which they leave the slide.
(B)
- frictional force due to mud,

<u>Now we find the force along the slide due to the body weight:</u>



<em><u>Hence the net force along the slide:</u></em>

<em>Now the acceleration of John:</em>



<u>Now the new velocity:</u>



Hence the new velocity is slower by

A. is the right answer since work is negative and Q which is heat in negative also
Explanation:
Light Light from a moving source travels at 300,000 km/sec (186,000 miles/sec).
Note:
The Speed of Light Is Constant.