1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

Velocity of a moving particle

  1. Mar 17, 2008 #1
    1. The problem statement, all variables and given/known data

    A particle moves down with position vector <sec(Pi*t), tan(Pi*t)> for
    0 =< t < 1/2.

    (a). Find the velocity and speed of the particle at t = 1/4.
    (b). The particle movies along a hyperbola. Elminate the parameter to find an equation of the hyperbola in terms of x and y.
    (c). Sketch the path of the particle over the time interval
    0 =< t < 1/2.

    2. Relevant equations

    ? none?

    3. The attempt at a solution

    velocity vector = < Pi*sec(Pi*t)tan(Pi*t), Pi*sec^2(Pi*t)>
    Plug in 1/4 into velocity vector:
    <.04307, Pi>

    Question is (part a), it's asking for velocity. I'm thinking writting velocity vector isn't the same thing; should I do a pythagorean theorem on the two components of my velocity vector to get a single value for velocity?

    Help appreciated :P
  2. jcsd
  3. Mar 17, 2008 #2
    I think you're confusing speed and velocity. Velocity is a vector, speed is not. So, the form you currently have the velocity in is sufficient. If you find the magnitude (i.e. what you call "doing a pythagorean theorem"), you'll have to also specify a direction, which is much more work than you need.
  4. Mar 17, 2008 #3
    Phew...so I just pull pythagorean for speed?
  5. Mar 17, 2008 #4
  6. Mar 17, 2008 #5
    Sweet! Thanks :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook