You need to remember that this requires vector addition (and subtraction). Starting with Vp/e = Vp/a + Va/e, rearrange to get: Va/e = Vp/e - Vp/a. The value for Vp/a is 220 Km/hr due west, or in cartesian coordinates: (-220i + 0j) Km/hr, where 'i' is the unit vector in the +x direction (+i = east and -i = west) and 'j' is the unit vector heading north (and hence -j is heading south). The vector Vp/e is found by determining the amount of ground covered per hour, which is (-240i - 40j)Km/hr; this comes from the position of the plane after 1/2 hour of travel. So we have:
Va/e = Vp/e - Vp/a = (-240i - 40j)Km/hr - (-220i + 0j)Km/hr = (-20i -40j)Km/hr
The magnitude of this wind velocity can be found using Pythagoras.
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Last edited by ChipB; Feb 11th 2013 at 06:43 AM.
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