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Homework Help: Energy conservation please?

  1. Jan 28, 2013 #1
    A man who was first standing runs from the point A.His speed is 40 m/s in B and 23 m/s in C,where the distance BC=30 meters..a) What work does the force of friction over the man ( m=60kg)? b) Find the max height reached by the man in the C level.. image here http://i.imgur.com/HVd7UH2.jpg

    I dont know how to find the quotient of the force of friction in the image? Because Work = -(quotient)* m*g*x.. I can find x because mv0^2/2+ +mv^2/2=mgh and I can find h,how about the quotient? does the angle help me?

    how about point b? please help me..
  2. jcsd
  3. Jan 28, 2013 #2


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    2017 Award

    Staff: Mentor

    That is not asked.

    What is the kinetic energy of the man in B and C? How does his potential energy change from B to C? You will see that the sum of both decreased - this difference is caused by friction.
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