Answer: D. There is a lot of light pollution on earth
Explanation: The light pollution on Earth has nothing to do with the stars in the sky
Answer:
25.3 ft
Explanation:
The illustration of the problem is shown the attached image.
The length of the ladder can be calculated using the Pythagoras theorem:

The hypotenuse is the length of the ladder.

........1
Triangle ABC is similar to triangle AEF, hence:

BC =
.................2
Substitute 2 into 1
=
+ 
Let AE = x
= 
= 
Minimize L with respect to x.
2
= 
=
The right half will be a new bar magnet of 2cm with north pole on the right side and south pole on teh left.