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Homework Help: Questions relating to motion in a plane

  1. Dec 29, 2006 #1
    1. The problem statement, all variables and given/known data

    I just would like to know if I'm using the right procedure to solve these problems.

    (a) Suzanne is skiing with a velocity of 18.0 m/s (N30.0 degrees W). What is the (N) component of her velocity vector?

    (b) TIm is running cross-country at 6.4 m/s (S) when he completes a wide turn and continues at 5.8 m/s (W). What is his change in velocity?

    2. Relevant equations
    Cos(theta) = adjacent / hypotenuse

    velocity = V2 - V1
    use of Pythagorean theorum formula

    3. The attempt at a solution

    (a) Given:
    velocity = 18.0 m/s
    30 degrees

    Required: Vn

    cos(theta) = adjacent/hypotenuse
    Cos30 degrees = Vn / 18 m/s
    Vn = (18.0 m/s) (Cos30 degrees)
    =15.6 m/s

    (b) Given:
    V1 = 6.4 m/s (E)
    V2 = 5.8 m/s W

    Required: change in velocity

    Analysis: velocity = V2 - V1
    =V2 + (-V1)
    =V2 - V1

    use the pythagorean theorum to determine the magintude of the velocity vector.
    V^2 = (5.8)^2 + (6.4)^2
    =33.64 + 40.96
    =74.6 m^2 s^2
    =8.64 m/s

    Then determine the direction of the velocity vector.
    Tan (theta) = 5.8 m/s / 6.4 m/s =0.91
    =42.3 degrees

    Therfore his change in velocity is 8.64 m/s (S 42.3 degrees W)

    Any help is always appreciated.
    Pharm 89:confused:
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Dec 30, 2006 #2


    User Avatar

    Your solution is right.
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