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Work and Energy of a sled

  1. Nov 13, 2007 #1
    1. The problem statement, all variables and given/known data

    You are pulling your sister on a sled to the top of a 17.0 m high, frictionless hill with a 10.0° incline. Your sister and the sled have a total mass of 50.0 kg. You pull the sled, starting from rest, with a constant force of 127 N at an angle of 45.0° to the hill. If you pull from the bottom to the top, what will the speed of the sled be when you reach the top?

    2. Relevant equations
    W=F*x (cos (angel))
    PE=mgh
    KE=1/2mv^2



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 13, 2007 #2

    G01

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    Do you have any work to show?
     
  4. Nov 13, 2007 #3
    You'll first need to figure out what the acceleration will be.

    Then you can solve for v using this equation:

    [tex]a(x-x_0)=\frac{1}{2}(v^2-v_0^2)[/tex]
     
  5. Nov 13, 2007 #4
    I'm not looking for an answer here. I know the answer, it is 4.29 m/s
    But can someone give me a step by step process on how to get that answer?
    Thanks
     
  6. Nov 13, 2007 #5

    G01

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    I'm sorry but that is not what we do here. The homework helpers HELP with homework. We do not give away solutions, which is essentially what you are asking for. If you would like we can help you figure out how to the correct answer, but you'll have to show some independent thought on the problem first. I'll get you started with some questions:

    You posted three relevant equations. Why did you decide to post those? How are they useful here?
     
  7. Nov 14, 2007 #6
    Step 1: draw a free body diagram of the scene.
    Step 2: Determine the forces acting on the object.
    Step 3: Find the acceleration of the object.
    Step 4: Find the velocity of the object based on distance and acceleration.
     
  8. Nov 14, 2007 #7
    Quick question:

    How do you calculate the change in internal energy given only the number of moles, and the temperature change?
     
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