Edwin Hubble calculated the expansion rate of the
universe. The evidence that he base his calculation is the differences in
redshift for galaxies. The answer is letter B. the red shift of galaxies was
directly proportional to the distance of the galaxy from earth. It means that bodies farther away from Earth
were moving away faster. The Hubble’s constant is the ratio of distance to
redshift equal to 170 kilometers per second per light year of distance.
Constant force - stays the same throughout
Variable force - changes throughout
Answer: No sure what to do
Explanation: points for points
<u>Answer</u>:
The stream flowing at a speed of 
<u>Explanation</u>:
Given:
Distance = 2km (both in upstream and downstream)
The speed in still water be x km/hr.
The speed in upstream = 4-x
Speed in downstream = 4+x
Solution:
We know that, Speed = distance/time
So, Time = distance/speed
Therefore,




By cancelling 2 on both sides,




Result:
Thus the speed of the stream is 