Snapshot & History Graphs


by bcjochim07
Tags: graphs, history, snapshot
bcjochim07
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#1
May9-08, 03:40 PM
P: 374
1. The problem statement, all variables and given/known data
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ID:	13913figure is asnapshot.jpg
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ID:	13914 correct & incorrect graphs is aasnapshot.jpg

Draw the history graph D(x=0m, t) at x= 0m for the wave shown in the figure.

2. Relevant equations



3. The attempt at a solution

I'm not quite understanding the concept of snapshot and history graphs. I think for this one the problem is that is is moving left. The graph that I drew is the wrong one. Here was my reasoning: In the figure, the graph is moving left, so shouldn't the leftmost point on the wave hit the point first? If at t=2 s this leftmost point is 1m away from x=0, then it takes 1 sec for it to arrive, so at t=3. I don't think I am visualizing this at all correctly. Could someone please explain to me why the graph on the bottom is correct? Thanks!
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bcjochim07
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#2
May9-08, 05:18 PM
P: 374
Any thoughts would be greatly appreciated.
bcjochim07
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#3
May9-08, 09:27 PM
P: 374
I am confused and this is really bothering me.

Redbelly98
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#4
May9-08, 11:38 PM
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Snapshot & History Graphs


Quote Quote by bcjochim07 View Post

3. The attempt at a solution

I'm not quite understanding the concept of snapshot and history graphs. I think for this one the problem is that is is moving left. The graph that I drew is the wrong one. Here was my reasoning: In the figure, the graph is moving left, so shouldn't the leftmost point on the wave hit the point first?
Yes.

If at t=2 s this leftmost point is 1m away from x=0, then it takes 1 sec for it to arrive, so at t=3.
Yes, nothing happens (at x=0 m) until t = 3 sec.

I don't think I am visualizing this at all correctly. Could someone please explain to me why the graph on the bottom is correct? Thanks!
It's not correct. At x = 0, D is 0 until t=3 sec. The graph labeled "wrong" looks like the right one to me.
bcjochim07
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#5
May9-08, 11:41 PM
P: 374
Yeah, see I'm having problems because there are a couple problems like this in my textbook where my drawings are completely off from what the back of the book has, so I was worried that I was not understanding this at all.
Redbelly98
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#6
May10-08, 12:28 AM
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Wow. What's the name of this book, and the authors? Looks like you understand it better than they do!
freshfruit007
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#7
Oct22-09, 02:11 AM
P: 1
My answer is the same as the original poster's..please, what are we doing wrong?!!??!
Redbelly98
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#8
Oct22-09, 06:35 AM
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Welcome to Physics Forums

You and the OP did it right, the book has it wrong.

What is the name of this book and its author?
Klorey
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#9
Nov1-09, 06:33 PM
P: 2
The book's called Physics for Scientists and Engineers: A Strategic Approach (2nd ed.), Vol 3, and the author is Randall D. Knight. I also got the same answer as the OP. So the book is wrong and the OP is right?
Redbelly98
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#10
Nov1-09, 06:39 PM
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Welcome to PF

Quote Quote by Klorey View Post
The book's called Physics for Scientists and Engineers: A Strategic Approach (2nd ed.), Vol 3, and the author is Randall D. Knight. I also got the same answer as the OP. So the book is wrong and the OP is right?
You are correct.

And thank you for answering my question
Klorey
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#11
Nov1-09, 06:52 PM
P: 2
No problem Thanks for the help (and the fast reply)!
Epsillon
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#12
Nov4-09, 12:53 AM
P: 70
I have the 6th edition of this book and the answer in the answer key is still wrong....


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