What does the use of the phrase "the lucky ones" convey about the author's viewpoint?
What does the phrase "But we never ate enough to
satisfy our hunger" demonstrate about the author?

1. He feels worse off.

2. His awareness of the grim situation.

Explanation:

Elie Weisel's memoir "Night" is about the persecution of the jews by the Germans during the worst genocide in world history. The events leading up to the Holocaust and the resulting after-effects through his personal experience provides one of the most prominent witness accounts of the crime.

When Weisel states that "lying down wasn't an option", he reveals how congested space was in the cabin. The "lucky ones" were able to breathe in the fresh air from the window, while the rest have to be satisfied with wherever they are. This reveals his realization of the grim situation inside the over-packed cabin, where there is hardly any space to move.

And when he said that they "never ate enough to satisfy our hunger", he presents the realization and understanding of the grim situation in the train's cabin where eating is not a luxury, but a necessity to stay alive. And for that, they know they have to "economize, to save for tomorrow" rather than just stay full once.  

i guess that visual aids present persuasive examples to what you are presenting, some factors would be theme (does it fit with the color, information, what you are presenting), size (can you see it, is it a big enough span of data/information), and overall look of the visual aid.

hope this : )

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.