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2D Kinematics Problem, Help Please

  • Thread starter creechur
  • Start date
  • #1
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Homework Statement


A particle starts from rest at (r0) = 9m j-hat and moves in the xy-plane with the velocity shown in the figure . The particle passes through a wire hoop located at (r1)=20m i-hat, then continues onward.

https://www.physicsforums.com/attachment.php?attachmentid=7841&stc=1&d=1159234661

The question I'm having trouble with is finding the y-component of velocity at t=4


Homework Equations



I think it's v = vi + ay delta t



The Attempt at a Solution



I got -40 (express to only one sig fig) and it was wrong, so I have no idea what to do


Someone please just point me in the direction to go, and not to an older thread
 

Answers and Replies

  • #2
Redbelly98
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The graphs are confusing. Both claim to be of vx as a function of time, but are clearly showing different functions. Can you explain more what the two graphs are supposed to be showing?
 
  • #3
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the first graph (positive V) is Vx the second one is vy
 
  • #4
Redbelly98
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Okay.

If that graph is the only information we have about vy, your question is unanswerable. Normally you would just read the value of vy at t=4 seconds on the graph. But whoever made the graph has done it sloppily, all we have is the cryptic "4y" label for the velocity at 4 seconds. Plus they mislabelled vx for the graph that should be vy.

Are these graphs something your professor provided in a printout? I can't believe a textbook would have something like this, since they normally have editors and proofreaders to troubleshoot errors like this.
 
  • #5
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It actually an online site that we do our homework on, I found those graphs elsewhere. I know it has something to do with the acceleration of gravity, but I submitted the answer 40 and got counted wrong (i submitted both negative and positive
 

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