Light bounces off a white cement sidewalk.
Particles generally can't pass through matter. All the other options show light moving through matter, except the space one. I don't think the space one is correct because particles normally don't move that fast.
Scientific form = 6.5 x 109.
It's average speed during that 26 seconds was about 4.77 m/s. Without seeing the graph, we can't tell if it was going faster or slower at any particular time during that period. All we can tell is its average for the full interval.
<span>Mechanical association learning used by an actor to memorize his lines</span>
Have you ever looked up the density of a substance ? You ought to try it. Go ahead. Pick a substance, then go online or open up an actual book and find its density. You will never see any particular volume mentioned along with the density . . . because it doesn't matter. The whole idea of density is that it describes the substance, no matter how much or how little you have of it. The density of a tiny drop of water under a microscope is the same as the density of a supertanker-ful of water.
