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Question on Newton's Second Law of Motion

  1. Sep 21, 2008 #1
    1. The problem statement, all variables and given/known data
    A space probe has two engines. Each generates the same amount of force when fired, and the directions of these forces can be independently adjusted. When the engines are fired simultaneously and each applies its force in the same direction, the probe, starting from rest, takes 28 seconds to travel a certain distance. How long does it take to travel the same distance , again starting from rest, if the engines are fired simultaneously and the forces that they apply to the probe are perpendicular?

    2. Relevant equations

    F = ma
    d = Vt + 1/2at^2

    3. The attempt at a solution

    I understand most of the question, but I am puzzled at how to find the acceleration when the two forces are perpendicular. I tried using the above equations, but I don't know exactly how to put everything together.
  2. jcsd
  3. Sep 21, 2008 #2
    When you find the acceleration of the rocket divide it by 2 to find the acceleration applied by each engine.

    If they are both perpendicular then they each make a 45 degree angle from their original positions.
    So their horizontal components will cancel out, don't bother finding those. and just find the vertical component of 1 of them and multiply by 2 to find the acceleration of the rocket.
    once you know that it should be easy to find the time.
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