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I don't know how to find tension in a cable

  1. Apr 19, 2013 #1
    I don't know hwo to find tension in a cable with two angles in the diagram.

    I have a car that weighs 1130kg held in place with a cable on a ramp that forms an angle of 25° above horizontal and the cable makes an angle of 31° above the surface of the ramp. I have to find the tension in the cable and I don't know how!! Please help
  2. jcsd
  3. Apr 19, 2013 #2


    Staff: Mentor

    Draw a force diagram first. You can see the gravitational force pulls down but the ramp changes things.

    Find the force of gravity pulling the car down break it into two components with one component along the ramp. That component and the tension T on the cable must add to zero.
  4. Apr 19, 2013 #3


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    Science Advisor
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    Gold Member

    jedishrfu - I don't think that's quite correct. The rope isn't parallel with the ramp.

    I would still approach it the same way. The car is stationary so the forces in any direction sum to zero. Lets choose the direction of the ramp that way the normal force of the car can be ignored.

    In the direction of the ramp you have two forces:

    1) A component of gravity
    2) A component of tension in the rope.

    These two sum to zero.
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