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Math Help - [SOLVED] Newton's Laws of Motion

  1. #1
    Senior Member
    Joined
    Feb 2008
    Posts
    383

    [SOLVED] Newton's Laws of Motion

    A particle P of mass 8 kg rests on a smooth plane inclined at 30 degrees to the horizontal. It is connected by a light inextensible string passing over a smooth light pulley at the top of the plane, to a particle of mass 3kg which is on a smooth plane inclined at 60 degrees to the horizontal.

    Find the acceleration of the system and the tension in the string.
    What I did is

    Code:
     T-8a=8gsin30
    Code:
     3a-T=3gsin60

    Used the calculator for simultaneous equation, which is not the answer in the back of the book. It should be 1.249m/s^2 and 29.21N. But i've got -64.25 and -12.9

    many thanks for your help!
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  2. #2
    Senior Member
    Joined
    Feb 2008
    Posts
    383
    Found the answer.
    Wasted so much time typing =.=""
    In my second equation
    Code:
     3a-T=3gsin60
    should be
    Code:
     3a+T=3gsin60
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