|
Post by En on Nov 14, 2003 7:27:46 GMT -5
Sphi, you rock. I love the way you did Dumbledore's line.
(hehe, did I tell you about this? www.livejournal.com/users/quislibet/164084.html )
Erm, did the bludger hit Harry squarely in the back or did it come in at an angle? *hides graphing calculator under table and tries to look innocent*
|
|
|
Post by Sphi on Nov 17, 2003 0:15:09 GMT -5
Hehe thanks. Can you read all of that? Or do you just get the jist of what I'm trying to say? I'm not that great, though. If I could translate any thing I see in one sitting without any help...then I would be impressed. *checks out that website* Heh, amazing what people will use Latin for. ;D
Nope, there's no angle. Keep working! I'd like to see if anyone can get it (but to be honest, if I were given this problem, I wouldn't know what to do...) Here's the image that went along with it, if this helps.
[/center]
|
|
|
Post by Icera on Nov 17, 2003 1:20:17 GMT -5
how fast was Harry moving at the time the bludger hit him? and does it hit him square in the back or his side or at an angle to his back? (note, these things actually matter in a question like this) cuz if he was hit from the side, he'd prolly just roll around the broom if it were too light; if from the back he might just fall forward and not fall off with any extra force; if he was hit at angle horizontally, he might fall off... ;D i'll actually look at the question when i get back home.
|
|
|
Post by Sphi on Nov 17, 2003 4:35:14 GMT -5
You're such a weirdo. how fast was Harry moving at the time the bludger hit him? That's something you have to figure out yourself. It's a multiple step problem, and there are two ways to solve it. The Bludger hits him squarely in the back, so no angle and not at the side. Got it?
|
|
|
Post by Rubes on Nov 18, 2003 19:02:58 GMT -5
How tall is the Big Ben Tower? I think I can work this out using projectile motion from Maths
Is Harry's horizontal velocity (before being hit)(highlight) 5.57 mph? If I knew the height he was hit at, I could work out the time of flight and hence the speed he hit the ground.
|
|
|
Post by Sphi on Nov 18, 2003 20:08:56 GMT -5
Oooh, I've sucked in more people. ;D
You're actually supposed to look that up, but this isn't Physics class, so I'll just give it to you: 92 m.
*blinks* Harry isn't moving at all at first. (Does that make the problem easier?) He's still and on the look-out when the Bludger hits him. So you have to calculate his velocity as soon as he's hit.
|
|
|
Post by Will on Nov 18, 2003 22:21:44 GMT -5
-nearly dies-
I'm not a math person, but that picture is just gorgeous! Or cute, rather. Did you draw it or that friend of yours?
-cough- Er... Well, then... Carry on with the physics problem.
|
|
|
Post by Rubes on Nov 18, 2003 22:39:15 GMT -5
Reasons why this won't be correct. 1) I'm not taking wight into consideration. Which is why 2) harry's initial speed after being struck by the Bludger is incorrect (I think )
Initial Conditions....
When time=0, x=0, y=46, ß=0, horizontal velocity=60, vertical velocity=0 ((g=9.8))
Maximum y value = 46 m
Therefore,
46 = V x V / 2g 46 x 2 x g = V x V 96 x 9.8 = V x V 901.6 = V x V V = 30.026654
Does Harry hit the ground at around 30 mph?
((If anybody knows the Initial Velocity, then everything will work))
|
|
|
Post by Sphi on Nov 19, 2003 23:58:45 GMT -5
*applause!* You got it!! Harry hits the ground at 30 m/s, but we assured the class that he was not hurt because of the magical-ness of the world. Your work looks a lot more simple than what we did. But then again, we had to implement certain ideas, and we had to solve it in two ways. The first step for both ways was using momentum. The second way was with either the motion equations or with energy equations. I don't know what you just did (although I probably should...test Friday ), but it came out right. I'm sure it makes sense, too, seeing how you're such a Physics pro. Good work!
So is y=V x V / 2g actually an equation? It looks sorta familiar...
Thanks, Willow! I drew that myself, with the help of my computer. I think that was the most fun part for me.
|
|
|
Post by Rubes on Nov 20, 2003 9:31:55 GMT -5
It's correct is it?
The working out is from Extension Maths, not Physics. However, the Time of Flight and Maximum Height Equations are the same.
If I knew how to type the little 'Square' symbol, this would be much easier
Maybe I should take a pic of my equations for you, although it's probably not a good idea to try and learn a new method just before an exam Speaking of which....I never have to do one ever again
|
|
|
Post by Sphi on Nov 22, 2003 2:29:04 GMT -5
Well, that's what my partner and I figured it to be (and we solved the problem in two different ways). Then we got our grade back for the presentation and problem, and although we still got an A, our teacher said that our solution was wrong, apparently. So Rubes, in my eyes, you couldn't be more correct. But my teacher wouldn't quite agree.
I've never even heard of Extension Math. I think I'll just concern myself with the Physics portion. (You know, you're a lucky duck for (1) being really good at math and sciences and (2) never having to take another test again. My exam today was not good. I'm so bad at Physics. >_< ) So is y=V x V / 2g a Physics equation? What does it do??
(Do you have Microsoft Word? Or some word processing program? You should be able to just copy and paste. That usually works.)
Ooh, yeah! I want to see how you worked this all out! Believe me, I probably won't understand it anyways. You can see our work (typed out), too. I do have a pic of one of my typical hand-written Latin homeworks. After I finished (a rare occasion), I was so astounded that I just had to take a picture before I mutilated it with correction marks.
|
|
|
Post by Rubes on Nov 22, 2003 3:36:06 GMT -5
Have you done Calculus? You'll need to know that first
I need to figure out how to get the notes on the computer....
Um um. I'll modify this when I figure out how to get the notes on
V x V is meant to be V squared; I just can't type it properly
What was the method that you used? Which equations did you need? Was Time of Flight one of them?
|
|
|
Post by Sphi on Nov 23, 2003 1:45:24 GMT -5
I'm taking Calculus at the moment, so I guess I'm not far enough to know what brilliant methods you're using. It would be interesting to see how you worked it out, though. Do you have a scanner, or even a digital camera?
Heh, yeah, I could tell what V x V was, but I still don't know what that equation is. I think I'm just abnormaly stupid. Some people in my class actually know what they're doing.
We were required to solve the problem in two ways. We used conservation of momentum as the first step for both ways,
mHvH = mBvB (6.5 kg)(27 m/s) = (70. kg)(vH) vH = 2.5 m/s
which was apparently not the right thing to do. For the second step, we used projectile motion the first time
vy^2 = vyo^2 – 2gy vy^2 = (2.5 m/s)^2 – 2(-9.80 m/s^2)(46 m) vy = 30. m/s
and conservation of energy the second time. (So, no, we never used time of flight.)
PE = (70. kg)(9.80 m/s^2)(46 m) = 32000 J ÄKE = ½(70. kg)(vf)^2 - ½(70. kg)(2.5 m/s)^2 PE = ÄKE ½(70. kg)(vf)^2 - ½(70. kg)(2.5 m/s)^2 = 32000 vf = 30. m/s
Therefore, both methods of solving came out with the same final velocity for Harry: 30. m/s. Not completely done correctly, I guess, but we were very excited when thinking all of this up. It's nice to be able to involved HP into my mundance life.
|
|
|
Post by Will on Dec 8, 2003 23:17:14 GMT -5
Uh-hm.... Backing away from physics and numbers in general...
I have found my official Hermoine. Not only does she have the personality, she also had the physical appearance. Ok, maybe not the teeth thing... Surprisingly, she has pretty frizzy brown hair. Yes, it's pretty and long... and smells good, yet frizzy at the same time. ((Erm, she's in my drama class... if that explains anything)) She practically knows her Shakespeare inside out.
|
|
|
Post by Tange-Rhi-ne, Tange-Rhi-ne on Feb 5, 2004 21:48:00 GMT -5
My Theology teacher reminds me of Umbridge, just not that evil. Even though she is really annoying But seriously, the first time I saw her, my first thought was "Umbridge." And she was semi-dictatorish right before midterms, saying how we shouldn't follow our own ideas, we should learn to answer how the textbook wants us to. By the way, this was a few weeks after telling us what a "personal thing" religion is, and how it's different to each person...oy.
|
|