1. Not finding help here? Sign up for a free 30min 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!

Motion in two dimensions Help!

  1. Feb 18, 2014 #1
    Motion in two dimensions!! Help!

    1. The problem statement, all variables and given/known data

    The coordinates of an object moving in the xy plane
    vary with time according to the equations x =-5.00 sin (vt) and y= 4.00 - 5.00 cos (vt),
    where v is a constant, x and y are in meters, and t is in seconds.
    (a) Determine the components of velocity of the
    object at t = 0. (b) Determine the components of
    acceleration of the object at t = 0. (c) Write expressions
    for the position vector, the velocity vector, and
    the acceleration vector of the object at any time t > 0.
    (d) Describe the path of the object in an xy plot.

    2. Relevant equations

    x =-5.00 sin (vt)
    y= 4.00 - 5.00 cos (vt),

    3. The attempt at a solution
    I was able to solve all the parts of this question except part d.
    I tried plotting the x y coordinates for different values of time, but the value of v is not provided. Should I consider some random value for v?
    P.S: v actually has the angular velocity symbol in my book. (the abnormal w).
     
  2. jcsd
  3. Feb 18, 2014 #2
    It is said that v is a constant, some certain angular velocity, it doesn't matter what it is. Could be pi radians/s or pi/2 radians/s or it could be 0 radians/s, it is constant.
    Sinusoid is a periodic function, they want you to plot what that 1 period looks like in an xy plane, most likely.
     
  4. Feb 18, 2014 #3
    So, I can assign any value for the angular velocity and then plot the curve using x and y coordiantes from different values of time?
     
  5. Feb 18, 2014 #4
    Yes, you can do that.
    Try plotting with different values for v, see if anything significantly changes or not.
     
  6. Feb 18, 2014 #5

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    The abnormal w is an omega, greek for big o. Big meaning long in this context. That's why they write two almost o's (they also have an omikron, small o, our current o).
    In PF these are available under advanced by simply clicking ω (or Ω - but not here because that is resistance for a physicist).

    A much better alternative is to use ## {\#}{\#} ## \omega, \Omega, \omicron, O, o ## {\#}{\#} ## to get ## \omega, \Omega, \omicron, O, o ##

    (My 1984 ##\TeX##book says there is no \omicron but now I discover it is there; but the \Omicron is not. Well, progress!)

    Oh, and: look through the problem. Would you recognize x = sin t, y = cos t ? If so, what about x and y-4 in your problem ?
     
  7. Feb 18, 2014 #6

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    So [itex]x= -5.00 sin(vt)[/itex] and [itex]y- 4.00= -5.00 cos(vt)[/itex]

    What is [itex]x^2+ (y- 4)^2[/itex]?

    What is the graph of that?

     
  8. Feb 19, 2014 #7

    yES I GOT IT! oNE THING THOUGH. if I GET SUCH QUESTIONS, DO WE ALWAYS HAVE TO THEN ELIMINATE THE (t) , in order to combine the x and y?
    (sorry for the caps lock part. I'm not shouting.)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Motion in two dimensions Help!
Loading...