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Homework Help: Physics help please

  1. Oct 18, 2004 #1
    Hello everyone. First I would just like to say how thankful I am that there is a forum for physics out here. Also I would like to prematurely thank anyone who is going to help me, it is greatly appreciated.

    Well I am in ap physics in high school, so this stuff should be cake for you guys.
    So I created a quick drawing of the picture, please excuse it, it was a little rushed. But there is a 100N street light hanging from two cables of equal length (in picture) The cables create a 37 degree angle with the top horizontal line. --What is the tension force of each cable?

    Could someone please explain to me how you find this, and does it make it easier because (or is it) an equalibrium system?

    My second qestion is if you have a 30kg mass on an inclined plane that is 30 degrees to the horizontal, and a 50kg mass that is 60 degrees to the horizontal. Both masses are released at the same time, which hits the ground first?

    And I have one final question (if I havent bugged you enough). If I have a mass tied to a string (pendulum) and it is at the bottom of its swing, how far will it have traveled if the mass is 1cm above the bottom of its swing, if the pendulum mass is .2kg?

    Again thank you so so much, and I appreciate any and all help

    Attached Files:

  2. jcsd
  3. Oct 19, 2004 #2
    Answer 1.

    You have to balence the 100N down with 100N up. Becouse there are 2 cabels and they have the same angel each of the cabels takes half of the 100N that's 50N. You can easily calculat the tension force of each cable with this equation
    sin37=50N/tension force
    tension force=50N/sin37

    See the ateched file.

    Attached Files:

  4. Oct 19, 2004 #3
    Answer 2.

    The second one its the ground first becouse of the angle (it has a larger acceleration towerds the ground). Mass is of no importance.

    Could you please be a bit more exact with your last question.
  5. Oct 19, 2004 #4
    Thanks Lenin.
    Sorry about the vagueness of the last problem. let me retype it. A pendulum with a mass of .2kg is at the bottom of its swing. what horizontal distance will it travel when the pendulum bob is 1cm above (vertically) its bottom most position.

    hopefully that is a little better.
  6. Oct 20, 2004 #5
    Thanks for your explination. As I see it the distance the pendulum travels is conected to its langht and not its mass. A long pendulum would travel further then a short one.
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