28. unbalanced forces cause an object to a) all of the answers are correct
b) move with constant velocity
c) speed up, slow down
d) be at rest

Explanation:

it causes it to speed up

hope this helps

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.

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the part of the wave he is travelling on is the crest