A jack requires 808 J of work to be done in raising a load, and ideally would do this amount of useful work. However, internal friction reduces the jack’s efficiency to 0.625. How much useful work is done by the jack?

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 : )

snell's law

refractve index = sin incidence / sin refraction