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Question about Force

  1. May 13, 2010 #1
    1. The problem statement, all variables and given/known data

    I need help solving this force problem: Two crewmen pull a raft through a lock. One person is pulling from a 45 degree angle above the horizontal and the other is pulling at a 35 degree angle below the horizontal with a force of 130N. the middle of the boat (laying horizontally) can be the horizontal reference for the angles. Also, both crewmen are pulling from the same end of the boat, and in the same horizontal direction so that the boat moves in the direction they pull. The question is, what force will the person pulling from the 45 degree angle have to exert to make the boat move in the desired direction (toward the pullers)?

    2. Relevant equations

    3. The attempt at a solution
    I know I have to make the x and y force components equal zero, I am having trouble understanding what to use (cos or sin) for each angle and what sign they should have.
  2. jcsd
  3. May 13, 2010 #2
    well basically you want to know the force int he horizontal direction, this means that it is adjacent to the angle the crewmen are pulling, from the SOH CAH TOA , we use the one that has cos @ = adjacent / hypotenuse .

    haha i just made the explanation sound long.... yeah use Cos, i just hope my explanation helped you understand the problem, better brush up on your trigonometry.

    basically the whole solution is find the adjacent, and then use the adjacent witht he 45 degree angle to find the hypotenuse for the other crewmen.

    Good Luck!!
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