1) The document discusses how relative velocity affects the movement of objects when they encounter wind or other forces. It uses the example of an airplane flying south at 300m/s encountering a 20m/s westerly wind. 2) Using vector addition, it calculates that the resultant velocity will be 301m/s at an angle of 3.81 degrees south of due south. 3) It then considers how to determine the direction the plane must fly to still travel south at 300m/s with the same 20m/s westerly wind, calculating it needs a heading of 183.2 degrees.

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