If a ball is rolling down a hill, it has both kinetic and potential energy. The ball has 38 J of potential energy because of its height and 80J of kinetic energy because
of its motion. How much mechanical energy does the ball have

The answer is 118 J :)

Explanation:

38 +80 = 118.

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 : )

their crystal patterns have been disrupted by stress