As some of you may know, I've got a lot of questions all the time... and so recently I've come up with a list of those I have yet to be answered, some of which I was able to sort out through a bit of googling, and searching my past threads, but here's what I couldn't quite manage to figure out with ease, although I should have some explanation of my thinking for each one: -About diffraction, I know that as a wave reaches a corner, it will bed around it, the deviation from it's straight path is dependent on the wavelength and the width of the opening or something like that anyway... The waves will always bend around, it's just that when the wavelength is small compared to the opening, not too much of the wave will bend, much will simply retain it's forward direction. Now what I'm wondering is if the point source of a wave for instance was right along the wall, would the waves still diffract around? I'm guessing they would, considering the point source would, albeit only a little, be directing the waves towards the opening. -Part 2 of my first one, say the point source of the wave was right in the wall, for example, a hole was carved into it, with a speaker placed inside... this is kind of hard to describe... but would the wave still bend around the corner then? I don't think it would, seeing as the waves coming from the speaker would automatically form a semicircle along the edge of the wall, and thus not be travelling in the direction of the opening at all... I don't know... is my thinking right on this one? -I saw this in a cartoon... don''t laugh, I don't know if it's real or not, that's why I'm asking; what would *theoretically* happen to a person travelling at a speed greater than that of light in a circular fashion? And, I don't know if it matters any, but what if it wasn't in a circle, but rather straight up and down? And straight forward? I haven't a clue on this one, in the cartoon, the character essentially melted. :surprised -When a roller coaster goes down a hill, it does this obviously because of gravity, the force pulling it down... but what about when it goes up a hill, what allows this to happen? I think it's momentum related, could be wrong though... and yes, I did some research on momentum before hand, learned the basics of it, if it's even related... -Last, I'm pretty sure, just confirm this for me... from one of my other threads, I learned exactly why you slip on ice, the friction you experience is kinetic friction, which is smaller than static friction, so I'm guessing this is why it's also hard to stop, right? When you apply the brakes... the force is small because it's kinetic friction as opposed to static friction. Not sure if it's right, but it;s just my thinking... also, why is the friction kinetic instead, and why is kinetic friction smaller than static friction? Well, that's all I have for now... I know there's a lot to sift through... but please someone help soon. I don't expect anyone to tackle all of the questions at once either... unless of course they're really basic and simple answers... but whatever you prefer. I just hope that I can recieve some help soon, and of course, with all my questions, thanks in advance.