<p>But why is it that wavelength stays the same? I mean the string length is the same, but what if there’s like 5 waves in it, while another string has 3 waves in it? Like then the waves would be different lengths?</p>
<p>Excuse my stupidity =P I know I got it wrong, but I’m still not sure how to go about it…</p>
<p>Coolio then.
@emmmei:
I thought the sled would stop after the dude stopped walking, because if it didn’t stop, it would be like: Sled and dude are stationary… BOOM sled is moving, dude is stationary. Then again, I do see your point of view. Maybe the dude applies force to stop the sled? idunno :p</p>
<p>The guitar string one: The wavelength stays the same because the string is tied down on both ends (both ends are nodes: they don’t move). For a guitar string, a pluck is only the simple standing wave, with the point in the middle of the line vibrating up and down (think jump rope viewed from the side). It can’t do crazy **** like a sin wave or having more than 1 crest in it (I just kind of logically reasoned this out; just imagine a string being plucked. There’s only a simple first harmonic wave, nothing crazy)… so the wavelength is 2L. Sorry for bad explanation XD</p>
<p>sled questions: for the first one, it is the person going towards the dock, the sled going away from the dock. the second one: both of them stop, velocity = 0
the guitar questions: 1) if it is one thick one thin, the thicker one has smaller frequency but equal wavelength 2) if the tension increases, wavelength stays the same but the frequency increases
thermometer questions: 1) the glass expands before the liquid does
2) the inside wall expands faster than the outside wall expands
sphere rotating question: people said velocity?</p>
<p>“Bad explanation”? YOU JUST CLEARED UP MY MIND!! Thank you so incredibly much =D
So the string can only have 1/2 of a wave… haha you’re right, can’t do crazy **** like a sin wave.</p>
<p>And I can totally see your point for the sled one. For some reason, I pictured myself in the person’s position, and the sled kept moving… I know, my imagination isn’t the most reliable resource for the SATs but oh well. </p>
<p>Thank you though!</p>
<p>Heh no problem 
And I’m not sure at all about the sled one. I’m not sure how the sled stops after the dude stops applying force. Maybe the dude continues moving forward and the sled continues backwards (the dude falls off?) Or, maybe the friction between the dude and the sled stops the sled? Meh, not sure at all XD</p>
<p>Haha me neither. It’s not force though… It’s momentum mv. I just can’t seem to prove that the sled keeps going =/</p>
<p>Gravity: you were right with the last explanation. The dude stopping changes his momentum, which caused an impulse and stops the sled (friction). Since momentum must be conserved, since no net EXTERNAL force was applied, the sled has to stop if the dude stops walking.</p>
<p>whats your speculation on the curve of this test?</p>
<p>hopefully super high! but i guess around 9 points off would be an 800…realistically…since they curve based on how everybody did and people are getting so good at physics nowadays</p>
<p>Really? The PR physics and blue book from years ago have -15 raw is an 800… but that is REALLY lenient…</p>
<p>yah but this test was like soo much harder than the practice tests (imo)
i feel like if it were the level of the practice tests, the curve would be like -7 = 800
IDK THOUGH. DONT COUNT ON ME</p>
<p>what did people get for the measurement error one?
25%
30%
?</p>
<p>I got 30 percent.</p>
<p>^i forgot what i put :(</p>
<p>I think I put 25%, but that’s a total guess. How did you do it?</p>
<p>if you actually calculate it you get 25%</p>
<p>So how did you actually calculate it? Did you just plug in the possible values and calculate the max and min for after? I was going to do that, but I was short on time, so I just guessed 25% and moved on.</p>
<p>When you multiply two numbers you add their percent error.</p>
<p>Yeah I calculated it too and got 25%. What was the actual question again?</p>
<p>uhh i forgot the actual numbers
but it was closer to 25 than 30
i hope hope hope that is right…this test was killer ]:<</p>
<p>I swear I got around 31%, so I put 30… but then again, my arithmetic is pathetic.</p>
<p>The first number was 10 +/- 5%
The second was bleh +/- 25%</p>
<p>If anyone could give the second number, that’d be awesome :D.</p>