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Homework Help: Projectiles, 2D Motion, displacement and average velocity

  1. Oct 23, 2009 #1
    1. The problem statement, all variables and given/known data

    A bird watcher meanders through the woods, walking 0.30 km due east, 0.65 km due south, and 2.25 km in a direction 37.0° north of west. The time required for this trip is 3.00 h. Determine the magnitude and direction (relative to due west) of the bird watcher's
    (a) displacement and
    1 km (magnitude)
    2° (direction north of west)
    (b) average velocity.
    3 km/h (magnitude)
    4° (direction north of west)
    Use kilometers and hours for distance and time, respectively.

    gravity: 9.8m/s^2

    2. Relevant equations
    Vf = Vi + A(D)T
    (D)X = Vi(D)T + (A(D)T^2)/2
    Vf^2 = Vi^2 + 2A(D)X

    3. The attempt at a solution
    I drew a diagram and i still don't know what to do.
  2. jcsd
  3. Oct 24, 2009 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    This is not an acceleration problem. It is just a matter of simple vector addition.

    What are the North-South and East-West components of the last leg of his trip. Add those to the first two displacements to get the final displacement. Then determine the angle and length of the final displacement.

    To find the average velocity, use the final displacement divided by time (3 hours).

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