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!

Homework Help: Change in x and y for a change in position

  1. Jan 18, 2007 #1
    Basically I have a pointer that starts at a particular reference point on a circle with cartisean coordinates,this pointer then moves around the circumference of the circle with an angle theta, the arc length is known but what I need to find is the change relative to x and y.

    I know that the arc length is given by;

    [tex]\delta c =r_{c}\theta_{a}[/tex]

    where [tex]\delta c, r_{c}, \theta_{a}[/tex] are the arc length, radius of the circle and the angle of the arc respectively.

    [tex]\delta c, r_{c}[/tex], and [tex]\theta_{a}[/tex] are known

    but what i don't know is how to find the new position of the pointer relative to x and y;

    hence I need to find the change in x and the change in y.

    I don't really know where to begin so if I could get some pointers rather than the answer then that would great.

    Thanks for your time

    Last edited: Jan 18, 2007
  2. jcsd
  3. Jan 18, 2007 #2
    A point on a circle with radii r could be represent by
    [tex] (rcos\theta ,rsin\theta) [/tex]
    in cartisean coodinate system....
    Now you are asking to find the different of x, and y coordinate when [tex] \theta [/tex] change from [tex] \theta_0 [/tex] to [tex] \theta_1 [/tex]
  4. Jan 18, 2007 #3
    Yes thats what i need to do I think. I attach a crude representation of what I am trying to find

    x and y are the unknowns


    Attached Files:

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook