1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

2D Kinematics Problem, Help Please

  1. Sep 3, 2009 #1
    1. The problem statement, all variables and given/known data
    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


    2. Relevant equations

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



    3. 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
     
  2. jcsd
  3. Sep 3, 2009 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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?
     
  4. Sep 3, 2009 #3
    the first graph (positive V) is Vx the second one is vy
     
  5. Sep 3, 2009 #4

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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.
     
  6. Sep 3, 2009 #5
    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
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: 2D Kinematics Problem, Help Please
Loading...