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Homework Help: Relative Velocity Raindrops

  1. Sep 24, 2012 #1
    1. The problem statement, all variables and given/known data
    When a train's velocity is 12.0 m/s eastward, raindrops that are falling vertically with respect to the earth make traces that are inclined 30.0 degrees to the verical on the windoes of the train.

    A. What is the horizontal componenet of a drop's velocity with respect to the earth?

    B. What is the horizontal component of a drops velocity with respect to the train?

    2. Relevant equations

    V(r/t) =V(r/g)+V(g/t)

    (r/t)= veolocity of rain with respect to the ground(earth)
    (g/t) velocity of the train with respect to the ground but negative.

    3. The attempt at a solution

    For part a well since it says the rain drops vertically with respect to the earth that must mean that it only has a vertical component.

    For part b I am not sure how I would go about that to calculate it.
  2. jcsd
  3. Sep 24, 2012 #2
    Do I break the vector of the rain into components?
  4. Sep 24, 2012 #3
    Just imagine looking at a window of the train.
    You see a raindrop just at the centre of top of the window and travels down.
    Where will the raindrop at the bottom of the window? Left, middle or right if the train is going to the right.
  5. Sep 24, 2012 #4
    to the left?
  6. Sep 24, 2012 #5
    It is to the left due to train velocity and down due to rain vertical velocity(down).
    If 1 sec. the train goes the right(12m) then you can find the vertical velocity using trig. function where opposite equal to 12 and the angle between adjacent and hypotenuse is 30°.
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