Register to reply

Snapshot & History Graphs

by bcjochim07
Tags: graphs, history, snapshot
Share this thread:
bcjochim07
#1
May9-08, 03:40 PM
P: 374
1. The problem statement, all variables and given/known data
Click image for larger version

Name:	asnapshot.jpg
Views:	218
Size:	4.3 KB
ID:	13913figure is asnapshot.jpg
Click image for larger version

Name:	aasnapshot.jpg
Views:	227
Size:	16.5 KB
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!
Phys.Org News Partner Science news on Phys.org
Hoverbike drone project for air transport takes off
Earlier Stone Age artifacts found in Northern Cape of South Africa
Study reveals new characteristics of complex oxide surfaces
bcjochim07
#2
May9-08, 05:18 PM
P: 374
Any thoughts would be greatly appreciated.
bcjochim07
#3
May9-08, 09:27 PM
P: 374
I am confused and this is really bothering me.

Redbelly98
#4
May9-08, 11:38 PM
Mentor
Redbelly98's Avatar
P: 12,064
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
#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
#6
May10-08, 12:28 AM
Mentor
Redbelly98's Avatar
P: 12,064
Wow. What's the name of this book, and the authors? Looks like you understand it better than they do!
freshfruit007
#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
#8
Oct22-09, 06:35 AM
Mentor
Redbelly98's Avatar
P: 12,064
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
#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
#10
Nov1-09, 06:39 PM
Mentor
Redbelly98's Avatar
P: 12,064
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
#11
Nov1-09, 06:52 PM
P: 2
No problem Thanks for the help (and the fast reply)!
Epsillon
#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....


Register to reply

Related Discussions
Very simple calculus problem...graphs and velocity/time graphs to acceleration. Calculus & Beyond Homework 1
Drawing velocity time graphs from distance-time graphs Introductory Physics Homework 2
Early history of gauge theory-a science history paper History & Humanities 1
Websites on Human Pre-history and history Social Sciences 0
Video snapshot - please help Computing & Technology 2