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Homework Help: Galilean transformation

  1. Feb 15, 2009 #1
    1. The problem statement, all variables and given/known data

    In a Summer's day, there's no wind, and start to rain. So the drops fall vertically for an observer on the ground. A car has a velocity of 10 Km/h and the driver see that the drops are coming perpendicularly to the windshield. If 60° is the angle between the windshield and the horizontal, determine:
    1) The velocity of the drops seen from the earth.
    2) The velocity of the drops when hits the windshield.

    2. Relevant equations

    [tex]v_D^C[/tex] = velocity of the drop for the driver

    [tex]v_C^G[/tex] = velocity of the car for an observer on the ground

    [tex]v_D^G[/tex] = velocity of the drop for an observer on the ground

    [tex]v_D^G = v_D^C + v_C^G[/tex]

    3. The attempt at a solution

    [tex]v_D^C = Xcos(330°) \hat{i} + Xsen(330°) \hat{j}[/tex]

    [tex]v_C^G = -10 \hat{i}[/tex]

    And because the drops are falling vertically:

    [tex]Xcos(330°) \hat{i} - 10 = 0[/tex]

    [tex]X = 11,55 km/h[/tex]

    Then, (1):

    [tex]|v_D^G |= Xsin(330) = -5,77 km/h[/tex]

    And finally (2):

    [tex]|v_D^C| = 11,55 km/h[/tex]

    I don't know if it is correct :P
  2. jcsd
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